Electrolytic solution and battery

ABSTRACT

A battery capable of improving high-temperature characteristics is provided. The battery includes a cathode, an anode and an electrolytic solution. A separator provided between the cathode and the anode is impregnated with the electrolytic solution. A solvent of the electrolytic solution includes a main solvent such as a cyclic carbonate which includes halogen and a sub solvent such as carbonate dimer.

CROSS REFERENCES TO RELATED APPLICATIONS

The present invention contains subject matter related to Japanese PatentApplication JP 2007-1134227 filed in the Japanese Patent Office on May21, 2007, the entire contents of which being incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electrolytic solution including asolvent and an electrolyte salt and a battery using the electrolyticsolution.

2. Description of the Related Art

In recent years, portable electronic devices such as camera-integratedVTRs (videotape recorders), cellular phones, or laptop computers arewidely used, and size and weight reduction in the portable electronicdevices and an increase in longevity of the portable electronic deviceshave been strongly demanded. Accordingly, as power sources for theportable electronic devices, the development of batteries, specificallylightweight secondary batteries capable of obtaining a high energydensity have been promoted. Among them, a secondary battery (a so-calledlithium-ion secondary battery) using insertion and extraction of lithiumfor charge-discharge reaction, a secondary battery (so-called lithiummetal secondary battery) using precipitation and dissolution of lithium,or the like holds great promise, because the secondary batteries arecapable of obtaining a large energy density, compared to a lead-acidbattery or a nickel-cadmium battery.

As an electrolytic solution for the lithium-ion secondary battery andthe lithium metal secondary battery, a combination of a carbonate-basedsolvent such as propylene carbonate or diethyl carbonate and anelectrolyte salt such as lithium hexafluorophosphate is widely used. Itis because the combination has high conductivity, and its potential isstable.

In addition, to improve various performance capabilities, sometechniques relating to the compositions of electrolytic solutions usedin these secondary batteries have already been proposed. Morespecifically, to improve cycle characteristics or safety, a technique ofincluding a chain carbonate including a halogen is known (for example,refer to Japanese Patent No. 3294400). Moreover, to improvehigh-temperature storage characteristics, initial charge-dischargecharacteristics, safety characteristics, cycle characteristics or thelike, techniques of including a chain carbonate dimer, a chaincarboxylate dimer, a chain sulfonate dimer, or a phosphate are known(for example, refer to Japanese Patent No. 3393620, and JapaneseUnexamined Patent Application Publication Nos. 2000-182669, 2001-085056,2004-079426, 2007-005242, 2006-351337, 2006-004746 and 2006-004747).Further, to improve cycle characteristics, a technique of including acyclic carbonate including a halogen and a chain carboxylate dimer isknown (for example, refer to Japanese Unexamined Patent ApplicationPublication No. 2006-172811).

SUMMARY OF THE INVENTION

Recently, electronic devices are distributed over a wide range offields, so secondary batteries tend to be exposed to a high-temperatureatmosphere during transport. Moreover, as the heating values ofelectronic devices increase because of factors such as enhancement ofperformance of electronic parts typified by CPUs (central processingunits), the secondary batteries in use tend to be exposed to ahigh-temperature atmosphere. These high-temperature environments cause adecline in the battery characteristics of the secondary batteries, andin particular, the high-temperature environments easily cause a declinein discharge capacity when the secondary batteries are stored at hightemperature, so further improvement in high-temperature characteristicsof the secondary batteries is desired.

In view of the foregoing, it is desirable to provide an electrolyticsolution capable of improving high-temperature characteristics, and abattery including the electrolytic solution.

According to an embodiment of the invention, there is provided anelectrolytic solution including: a solvent; and an electrolyte salt, inwhich the solvent includes: at least one kind selected from the groupconsisting of a cyclic carbonate represented by Chemical Formula 1 whichincludes a halogen and a chain carbonate represented by Chemical Formula2 which includes a halogen; and at least one kind selected from thegroup consisting of compounds represented by Chemical Formulas 3, 4 and5.

where R1, R2, R3 and R4 each represent a hydrogen group, a halogengroup, an alkyl group or a halogenated alkyl group, and at least one ofthem is a halogen group or a halogenated alkyl group.

where R11, R12, R13, R14, R15 and R16 each represent a hydrogen group, ahalogen group, an alkyl group or a halogenated alkyl group, and at leastone of them is a halogen group or a halogenated alkyl group.

where R21 and R23 each represent an alkyl group, an alkenyl group, analkynyl group, an aryl group, a heterocyclic group, or an alkyl group,an alkenyl group or an alkynyl group substituted with an aromatichydrocarbon group or an alicyclic hydrocarbon group, or a group formedby halogenating any one of them, and R22 represents a straight-chain orbranched alkylene group, an arylene group, a divalent group including anarylene group and an alkylene group, a divalent group with 2 to 12carbon atoms which includes an ether bond and an alkylene group, or agroup formed by halogenating any one of them.

where R31 and R33 each represent an alkyl group, an alkenyl group, analkynyl group, an aryl group, a heterocyclic group, or an alkyl group,an alkenyl group or an alkynyl group substituted with an aromatichydrocarbon group or an alicyclic hydrocarbon group, or a group formedby halogenating any one of them, and R32 represents a straight-chain orbranched alkylene group, an arylene group, a divalent group including anarylene group and an alkylene group, a divalent group with 2 to 12carbon atoms which includes an ether bond and an alkylene group, or agroup formed by halogenating any one of them.

where R41 and R43 each represent an alkyl group, an alkenyl group, analkynyl group, an aryl group, a heterocyclic group, or an alkyl group,an alkenyl group or an alkynyl group substituted with an aromatichydrocarbon group or an alicyclic hydrocarbon group, or a group formedby halogenating any one of them, and R42 represents a straight-chain orbranched alkylene group, an arylene group, a divalent group including anarylene group and an alkylene group, a divalent group with 2 to 12carbon atoms which includes an ether bond and an alkylene group, or agroup formed by halogenating any one of them.

According to an embodiment of the invention, there is provided a batteryincluding a cathode, an anode and an electrolytic solution, in which theelectrolytic solution includes a solvent and an electrolyte salt, andthe solvent includes: at least one kind selected from the groupconsisting of a cyclic carbonate represented by Chemical Formula 6 whichincludes a halogen and a chain carbonate represented by Chemical Formula7 which includes a halogen; and at least one kind selected from thegroup consisting of compounds represented by Chemical Formulas 8, 9 and10.

where R1, R2, R3 and R4 each represent a hydrogen group, a halogengroup, an alkyl group or a halogenated alkyl group, and at least one ofthem is a halogen group or a halogenated alkyl group.

where R11, R12, R13, R14, R15 and R16 each represent a hydrogen group, ahalogen group, an alkyl group or a halogenated alkyl group, and at leastone of them is a halogen group or a halogenated alkyl group.

where R21 and R23 each represent an alkyl group, an alkenyl group, analkynyl group, an aryl group, a heterocyclic group, or an alkyl group,an alkenyl group or an alkynyl group substituted with an aromatichydrocarbon group or an alicyclic hydrocarbon group, or a group formedby halogenating any one of them, and R22 represents a straight-chain orbranched alkylene group, an arylene group, a divalent group including anarylene group and an alkylene group, a divalent group with 2 to 12carbon atoms which includes an ether bond and an alkylene group, or agroup formed by halogenating any one of them.

where R31 and R33 each represent an alkyl group, an alkenyl group, analkynyl group, an aryl group, a heterocyclic group, or an alkyl group,an alkenyl group or an alkynyl group substituted with an aromatichydrocarbon group or an alicyclic hydrocarbon group, or a group formedby halogenating any one of them, and R32 represents a straight-chain orbranched alkylene group, an arylene group, a divalent group including anarylene group and an alkylene group, a divalent group with 2 to 12carbon atoms which includes an ether bond and an alkylene group, or agroup formed by halogenating any one of them.

where R41 and R43 each represent an alkyl group, an alkenyl group, analkynyl group, an aryl group, a heterocyclic group, or an alkyl group,an alkenyl group or an alkynyl group substituted with an aromatichydrocarbon group or an alicyclic hydrocarbon group, or a group formedby halogenating any one of them, and R42 represents a straight-chain orbranched alkylene group, an arylene group, a divalent group including anarylene group and an alkylene group, a divalent group with 2 to 12carbon atoms which includes an ether bond and an alkylene group, or agroup formed by halogenating any one of them.

In the electrolytic solution according to the embodiment of theinvention, the solvent includes at least one kind selected from thegroup consisting of a cyclic carbonate represented by Chemical Formula 1which includes a halogen and a chain carbonate represented by ChemicalFormula 2 which includes a halogen, and at least one kind selected fromthe group consisting of compounds represented by Chemical Formulas 3, 4and 5, so chemical stability is improved. Thereby, in a batteryincluding the electrolytic solution according to the embodiment of theinvention, the decomposition of the electrolytic solution is prevented,so high-temperature characteristics such as storage characteristics maybe improved.

Other and further objects, features and advantages of the invention willappear more fully from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing the configuration of a first batteryusing an electrolytic solution according to an embodiment of theinvention;

FIG. 2 is a partially enlarged sectional view of a spirally woundelectrode body shown in FIG. 1;

FIG. 3 is an exploded perspective view of a fourth battery using theelectrolytic solution according to the embodiment of the invention;

FIG. 4 is a sectional view showing a spirally wound electrode body takenalong a line IV-IV of FIG. 3; and

FIG. 5 is a sectional view showing the configuration of a fifth batteryusing the electrolytic solution according to the embodiment of theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment will be described in detail below referring tothe accompanying drawings.

An electrolytic solution according to an embodiment of the invention isused in, for example, an electrochemical device such as a battery, andincludes a solvent and an electrolyte salt.

The solvent includes a main solvent and a sub solvent. The main solventincludes at least one kind selected from the group consisting of acyclic carbonate represented by Chemical Formula 11 which includes ahalogen as an element and a chain carbonate represented by ChemicalFormula 12 which includes a halogen as an element. The sub solventincludes at least one kind selected from the group consisting ofcompounds represented by Chemical Formulas 13, 14 and 15. It is becausewhen the solvent includes the main solvent and the sub solvent together,the chemical stability of the electrolytic solution is improved.

where R1, R2, R3 and R4 each represent a hydrogen group, a halogengroup, an alkyl group or a halogenated alkyl group, and at least one ofthem is a halogen group or a halogenated alkyl group.

where R11, R12, R13, R14, R15 and R16 each represent a hydrogen group, ahalogen group, an alkyl group or a halogenated alkyl group, and at leastone of them is a halogen group or a halogenated alkyl group.

where R21 and R23 each represent an alkyl group, an alkenyl group, analkynyl group, an aryl group, a heterocyclic group, or an alkyl group,an alkenyl group or an alkynyl group substituted with an aromatichydrocarbon group or an alicyclic hydrocarbon group, or a group formedby halogenating any one of them, and R22 represents a straight-chain orbranched alkylene group, an arylene group, a divalent group including anarylene group and an alkylene group, a divalent group with 2 to 12carbon atoms which includes an ether bond and an alkylene group, or agroup formed by halogenating any one of them.

where R31 and R33 each represent an alkyl group, an alkenyl group, analkynyl group, an aryl group, a heterocyclic group, or an alkyl group,an alkenyl group or an alkynyl group substituted with an aromatichydrocarbon group or an alicyclic hydrocarbon group, or a group formedby halogenating any one of them, and R32 represents a straight-chain orbranched alkylene group, an arylene group, a divalent group including anarylene group and an alkylene group, a divalent group with 2 to 12carbon atoms which includes an ether bond and an alkylene group, or agroup formed by halogenating any one of them.

where R41 and R43 each represent an alkyl group, an alkenyl group, analkynyl group, an aryl group, a heterocyclic group, or an alkyl group,an alkenyl group or an alkynyl group substituted with an aromatichydrocarbon group or an alicyclic hydrocarbon group, or a group formedby halogenating any one of them, and R42 represents a straight-chain orbranched alkylene group, an arylene group, a divalent group including anarylene group and an alkylene group, a divalent group with 2 to 12carbon atoms which includes an ether bond and an alkylene group, or agroup formed by halogenating any one of them.

In addition, R1 to R4 in Chemical Formula 11 may be the same as ordifferent from one another. The same holds for R11 to R16 in ChemicalFormula 12. Moreover, R21 and R23 in Chemical Formula 13 may be the sameas or different from each other. The same holds for R31 and R33 inChemical Formula 14, and R41 and R43 in Chemical Formula 15. The “groupformed by halogenating any one of them” described in Chemical Formulas13 to 15 means a group formed by substituting a halogen group for atleast a part of a hydrogen group, and the same holds for ChemicalFormula 26 which will be described later.

Specific compositions of the cyclic carbonate represented by ChemicalFormula 11 which includes a halogen, the chain carbonate represented byChemical Formula 12 which includes a halogen, the compounds representedby Chemical Formulas 13, 14 and 15 will be described in detail below.

In the case where the electrolytic solution is used for anelectrochemical device, the cyclic carbonate represented by ChemicalFormula 11 which includes a halogen and the chain carbonate representedby Chemical Formula 12 which includes a halogen forms a film (a halide)on a surface of an electrode so as to improve the chemical stability ofthe electrolytic solution. The number of halogens is preferably two ormore. It is because a strong and stable film is formed, compared to thecase where the number of halogens is 1, so a higher effect may beobtained.

In the case where at least one of R1 to R4 represented by ChemicalFormula 11 is an alkyl group or a halogenated alkyl group, as R1 to R4,a methyl group, an ethyl group, a halogenated methyl group, ahalogenated ethyl group or the like is preferable, because a sufficienteffect may be obtained.

Examples of the cyclic carbonate represented by Chemical Formula 11which includes a halogen include compounds represented by ChemicalFormulas 16 and 17. More specifically, 4-fluoro-1,3-dioxolane-2-one inChemical Formula 16(1), 4-chloro-1,3-dioxolane-2-one in Chemical Formula16(2), 4,5-difluoro-1,3-dioxolane-2-one in Chemical Formula 16(3),tetrafluoro-1,3-dioxolane-2-one in Chemical Formula 16(4),4-fluoro-5-chloro-1,3-dioxolane-2-one in Chemical Formula 16(5),4,5-dichloro-1,3-dioxolane-2-one in Chemical Formula 16(6),tetrachloro-1,3-dioxolane-2-one in Chemical Formula 16(7),4,5-bistrifluoromethyl-1,3-dioxolane-2-one in Chemical Formula 16(8),4-trifluoromethyl-1,3-dioxolane-2-one in Chemical Formula 16(9),4,5-difluoro-4,5-dimethyl-1,3-dioxolane-2-one in Chemical Formula16(10), 4-methyl-5,5-difluoro-1,3-dioxolane-2-one in Chemical Formula16(11), 4-ethyl-5,5-difluoro-1,3-dioxolane-2-one in Chemical Formula16(12) and the like are cited. Moreover,4-trifluoromethyl-5-fluoro-1,3-dioxolane-2-one in Chemical Formula17(1), 4-trifluoromethyl-5-methyl-1,3-dioxolane-2-one in ChemicalFormula 17(2), 4-fluoro-4,5-dimethyl-1,3-dioxolane-2-one in ChemicalFormula 17(3), 4,4-difluoro-5-(1,1-difluoroethyl)-1,3-dioxolane-2-one inChemical Formula 17(4), 4,5-dichloro-4,5-dimethyl-1,3-dioxolane-2-one inChemical Formula 17(5), 4-ethyl-5-fluoro-1,3-dioxolane-2-one in ChemicalFormula 17(6), 4-ethyl-4,5-difluoro-1,3-dioxolane-2-one in ChemicalFormula 17(7), 4-ethyl-4,5,5-trifluoro-1,3-dioxolane-2-one in ChemicalFormula 17(8), 4-fluoro-4-trifluoromethyl-1,3-dioxolane-2-one inChemical Formula 17(9),4,5-bistrifluoromethyl-4,5-difluoro-1,3-dioxolane-2-one in ChemicalFormula 17(10), 4-bromo-1,3-dioxolane-2-one in Chemical Formula 17(11)and the like are cited. Only one kind or a mixture of a plurality ofkinds selected from them may be used. Among them, at least one kindselected from 4-fluoro-1,3-dioxolane-2-one and4,5-difluoro-1,3-dioxolane-2-one is preferable, and4,5-difluoro-1,3-dioxolane-2-one is more preferable. It is because theyare easily available, and a higher effect may be obtained. Inparticular, as 4,5-difluoro-1,3-dioxolane-2-one, a trans-isomer is morepreferable than a cis-isomer. As long as the cyclic carbonate has thecomposition represented by Chemical Formula 11, the cyclic carbonate isnot limited to the above-described compounds.

Examples of the chain carbonate represented by Chemical Formula 12 whichinclude a halogen include bis(fluoromethyl)carbonate, fluromethyl methylcarbonate, difluoromethyl methyl carbonate and the like. Only one kindor a mixture of a plurality of kinds selected from them may be used.Among them, bis(fluoromethyl)carbonate is preferable, because asufficient effect may be obtained. As long as the chain carbonate hasthe composition represented by Chemical Formula 12, the chain carbonateis not limited to the above-described compounds.

The content of the compounds represented by Chemical Formulas 13 to 15as the sub solvents is preferably within a range from 0.001 wt % to 10wt % both inclusive, because a sufficient effect may be obtained. Morespecifically, the content is more preferably within a range from 0.01 wt% to 1 wt % both inclusive, and particularly preferably within a rangefrom 0.1 wt % to 1 wt % both inclusive, because a higher effect may beobtained.

The molecular weight of the compound represented by Chemical Formula 13is preferably within a range from 200 to 800 both inclusive, morepreferably within a range from 200 to 600 both inclusive, andparticularly preferably within a range from 200 to 450 both inclusive.It is because a sufficient effect may be obtained, and sufficientsolubility and sufficient compatibility may be obtained.

Examples of R21 and R23 represented by Chemical Formula 13 include thefollowing groups.

As the alkyl group, a methyl group, an ethyl group, an n (normal)-propylgroup, an isopropyl group, an n-butyl group, an isobutyl group, a sec(secondary)-butyl group, a tert (tertiary)-butyl group, an n-pentylgroup, a 2-methylbutyl group, a 3-methylbutyl group, a 2,2-dimethylpropyl group, an n-hexyl group or the like is cited. As the alkenylgroup, an n-heptyl group, a vinyl group, a 2-methylvinyl group, a2,2-dimethyl vinyl group, a butane-2,4-diyl group, an allyl group or thelike is cited. As the alkynyl group, an ethynyl group or the like iscited. The number of carbon atoms in the alkyl group, the alkenyl groupor the alkynyl group is preferably within a range from 1 to 20 bothinclusive, more preferably within a range from 1 to 7 both inclusive,and particularly preferably within a range from 1 to 4 both inclusive.It is because a sufficient effect may be obtained, and sufficientcompatibility may be obtained.

In the case where the alkyl group, the alkenyl group or the alkynylgroup is substituted with an aromatic hydrocarbon group or an alicyclichydrocarbon group, as the aromatic hydrocarbon group, a phenyl group orthe like is cited, and as the alicyclic hydrocarbon group, a cyclohexylgroup or the like is cited. Among them, as an alkyl group substitutedwith a phenyl group (a so-called aralkyl group), for example, a benzylgroup, a 2-phenyl ethyl group (a phenethyl group) or the like is cited.

As an alkyl group substituted with a halogen (a halogenated alkylgroup), a fluorinated alkyl group is cited. As the fluorinated alkylgroup, a fluoromethyl group, a difluoromethyl group, a trifluoromethylgroup, a 2,2,2-trifluoroethyl group, a pentafluoroethyl group or thelike is cited.

Among them, an alkyl group or the like substituted with an aromatichydrocarbon group or an alicyclic hydrocarbon group is more preferablethan an alkyl group or the like substituted with a halogen, and an alkylgroup or the like not substituted with an aromatic hydrocarbon group oran alicyclic hydrocarbon group is more preferable. In the alkyl group orthe like substituted with an aromatic hydrocarbon group or an alicyclichydrocarbon group, the total of the number of carbon atoms in thearomatic hydrocarbon group or the alicyclic hydrocarbon group and thenumber of carbon atoms in the alkyl group or the like is preferably 20or less, and more preferably 7 or less.

In the case where R22 in Chemical Formula 13 is a straight-chain orbranched alkylene group, an arylene group or a divalent group includingan arylene group and an alkylene group, the numbers of carbon atoms inthese group is freely settable; however, the numbers of carbon atoms inthese group are preferably within a range from 2 to 10 both inclusive,and more preferably within a range from 2 to 6 both inclusive, andparticularly preferably within a range from 2 to 4 both inclusive. It isbecause a sufficient effect may be obtained, and sufficientcompatibility may be obtained. The divalent group including an arylenegroup and an alkylene group may be a divalent group in which one arylenegroup and one alkylene group are linked, or a divalet group (anaralkylene group) in which two alkylene groups are linked through anarylene group.

As R22 in this case, for example, straight-chain alkylene groupsrepresented by Chemical Formulas 18(1) to 18(7), branched alkylenegroups represented by Chemical Formulas 19(1) to 19(9), arylene groupsrepresented by Chemical Formulas 20(1) to 20(3), divalent groupsincluding an arylene group and an alkylene group represented by ChemicalFormulas 20(4) to 20(6) and the like are cited. The divalent groups inChemical Formulas 20(4) to 20(6) are so-called benzylidene groups.

Moreover, in the case where R22 is a divalent group with 2 to 12 carbonatoms which includes an ether bond and an alkylene group, a group inwhich at least two alkylene groups are linked through an ether bond, andcarbon atoms are located at ends of the group is preferable. The numberof carbon atoms in this case is preferably within a range from 4 to 12both inclusive. It is because a sufficient effect may be obtained, andsufficient compatibility may be obtained. In addition, in a divalentgroup with 2 to 12 carbon atoms which includes an ether bond and analkylene group, the number of ether bonds and the order in which anether bond and an alkylene group are linked are freely settable.

As R22 in this case, for example, divalent groups represented byChemical Formulas 21(1) to 21(13) and the like are cited. In the casewhere the divalent groups in the Chemical Formula 21 are fluorinated, asR22, for example, divalent groups represented by Chemical Formulas 22(1)to 22(9) and the like are cited. Among them, divalent groups representedby Chemical Formulas (21)(6) to (8) are preferable.

As a specific example of the compound represented by Chemical Formula13, a compound represented by Chemical Formula 23 or the like is cited,because a sufficient effect may be obtained. As long as the compound hasa composition represented by Chemical Formula 13, the compound is notlimited to the compound represented by Chemical Formula 23.

The molecular weight of the compound represented by Chemical Formula 14is preferably within a range from 162 to 1000 both inclusive, and morepreferably within a range from 162 to 500 both inclusive, andparticularly preferably within a range from 162 to 300 both inclusive.It is because a sufficient effect may be obtained, and sufficientcompatibility may be obtained. Specific examples of R31 and R33represented by Chemical Formula 14 are the same as the above-describedexamples of R21 and R23 represented by Chemical formula 13. Moreover,specific examples of R32 represented by Chemical Formula 14 are the sameas the above-described examples of R22 represented by Chemical Formula13. As a specific example of the compound represented by ChemicalFormula 14, a compound represented by Chemical Formula 24 or the like iscited, because a sufficient effect may be obtained. In addition to this,diethylene glycol dipropionate, diethylene glycol dibutyrate,triethylene glycol diacetate, triethylene glycol dipropionate,triethylene glycol dibutyrate, tetraethylene glycol diacetate,tetraethylene glycol dipropionate, tetraethylene glycol dibutyrate orthe like is cited. As long as the compound has a composition representedby Chemical Formula 14, the compound is not limited to theabove-described compounds.

The molecular weight of the compound represented by Chemical Formula 15is preferably within a range from 200 to 800 both inclusive, morepreferably within a range from 200 to 600 both inclusive, andparticularly preferably within a range from 200 to 450 both inclusive.It is because a sufficient effect may be obtained, and sufficientsolubility and sufficient compatibility may be obtained. Specificexamples of R41 and R43 represented by Chemical Formula 15 are the sameas the above-described specific examples of R21 and R23 represented byChemical Formula 13. Moreover, specific examples of R42 represented byChemical Formula 15 are the same as the above-described specificexamples of R22 represented by Chemical Formula 13. As a specificexample of the compound represented by Chemical Formula 15, a compoundrepresented by Chemical Formula 25 or the like is cited. It is because asufficient effect may be obtained. As long as the compound has acomposition represented by Chemical Formula 15, the compound is notlimited to the compound represented by Chemical Formula 25.

Moreover, the main solvent may include a nonaqueous solvent such asother organic solvent in addition to at least one kind selected from thegroup consisting of the cyclic carbonate represented by Chemical Formula11 which includes a halogen and the chain carbonate represented byChemical Formula 12 which includes a halogen. Examples of the nonaqueoussolvent include ethylene carbonate, propylene carbonate, butylenecarbonate, dimethyl carbonate, diethyl carbonate, ethyl methylcarbonate, methyl propyl carbonate, γ-butyrolactone, γ-valerolactone,1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran,tetrahydropyran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane,1,4-dioxane, methyl acetate, ethyl acetate, methyl propionate, ethylpropionate, methyl butyrate, methyl isobutyrate, methyltrimethylacetate, ethyl trimethylacetate, acetonitrile, glutaronitrile,adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile,N,N-dimethylformamide, N-methylpyrrolidinone, N-methyloxazolidinone,N,N′-dimethyl imidazolidinone, nitromethane, nitroethane, sulfolane,trimethyl phosphate, dimethyl sulfoxide, dimethyl sulfoxide phosphateand the like. Only one kind or a mixture of a plurality of kindsselected from them may be used. Among them, the main solvent preferablyincludes at least one kind selected from the group consisting ofethylene carbonate, propylene carbonate, dimethyl carbonate, diethylcarbonate and ethyl methyl carbonate, because a sufficient effect may beobtained. In this case, in particular, the main solvent preferablyincludes a mixture of a high-viscosity (high-permittivity) solvent (forexample, relative permittivity ε≥30) such as ethylene carbonate orpropylene carbonate and a low-viscosity solvent (for example,viscosity≤1 mPa·s) such as dimethyl carbonate, ethyl methyl carbonate ordiethyl carbonate. It is because the dissociation property of theelectrolyte salt and ion mobility are improved, so a higher effect maybe obtained.

The solvent may further include an auxiliary solvent. The auxiliarysolvent preferably includes a compound represented by Chemical Formula26. It is because the chemical stability of the electrolytic solution isfurther improved. The content of the auxiliary solvent in the solvent ispreferably within a range from 0.001 wt % to 1 wt % both inclusive,because a sufficient effect may be obtained.

where R51, R52 and R53 each represent an alkyl group, an alkenyl group,an alkynyl group, an aryl group, a heterocyclic group, or an alkylgroup, an alkenyl group or alkynyl group substituted with an aromatichydrocarbon group or alicyclic hydrocarbon group, or a group formed byhalogenating any one of them.

The molecular weight of the compound represented by Chemical Formula 26is preferably within a range from 200 to 800 both inclusive, morepreferably within a range from 200 to 600 both inclusive, andparticularly preferably within a range from 200 to 450 both inclusive.It is because a sufficient effect may be obtained, and sufficientcompatibility may be obtained. Specific examples of R51, R52 and R53represented by Chemical Formula 26 are the same as the specific examplesof R21 and R23 represented by Chemical Formula 13.

As a specific example of the compound represented by Chemical Formula26, a compound represented by Chemical Formula 27 or the like is cited.As long as the compound has a composition represented by ChemicalFormula 26, the compound is not limited to the compound represented byChemical Formula 27.

Moreover, the solvent preferably includes a cyclic carbonate includingan unsaturated bond as another solvent, because the chemical stabilityof the electrolytic solution is further improved. The content of thecyclic carbonate including an unsaturated bond in the solvent ispreferably within a range from 0.01 wt % to 5 wt % both inclusive,because a sufficient effect may be obtained. As the cyclic carbonateincluding an unsaturated bond, for example, at least one kind selectedfrom the group consisting of a vinylene carbonate-based compound, avinyl ethylene carbonate-based compound and a methylene ethylenecarbonate-based compound, or the like is cited.

Examples of the vinylene carbonate-based compound include vinylenecarbonate (1,3-dioxol-2-one), methyl vinylene carbonate(4-methyl-1,3-dioxol-2-one), ethyl vinylene carbonate(4-ethyl-1,3-dioxol-2-one), 4,5-dimethyl-1,3-dioxol-2-one,4,5-diethyl-1,3-dioxol-2-one, 4-fluoro-1,3-dioxol-2-one,4-trifluoromethyl-1,3-dioxol-2-one and the like.

Examples of the vinyl ethylene carbonate-based compound include vinylethylene carbonate (4-vinyl-1,3-dioxolane-2-one),4-methyl-4-vinyl-1,3-dioxolane-2-one,4-ethyl-4-vinyl-1,3-dioxolane-2-one,4-n-propyl-4-vinyl-1,3-dioxolane-2-one,5-methyl-4-vinyl-1,3-dioxolane-2-one, 4,4-divinyl-1,3-dioxolane-2-one,4,5-divinyl-1,3-dioxolane-2-one and the like.

Examples of the methylene ethylene carbonate-based compound include4-methylene-1,3-dioxolane-2-one,4,4-dimethyl-5-methylene-1,3-dioxolane-2-one,4,4-diethyl-5-methylene-1,3-dioxolane-2-one and the like.

Only one kind or a mixture of a plurality of kinds selected from themmay be used. Among them, as the cyclic carbonate including anunsaturated bond, vinylene carbonate is preferable, because a sufficienteffect may be obtained.

Further, the solvent preferably includes a sultone (a cyclic sulfonate)or an acid anhydride, because the chemical stability of the electrolyticsolution is further improved. The content of the sultone in the solventis preferably within a range from 0.5 wt % to 3 wt % both inclusive,because a sufficient effect may be obtained. Examples of the sultoneinclude propane sultone, propene sultone and the like. Only one kind ora mixture of a plurality of kinds selected from them may be used. Amongthem, propene sultone is preferable, because a sufficient effect may beobtained.

The content of the acid anhydride in the solvent is preferably within arange from 0.5 wt % to 3 wt % both inclusive, because a sufficienteffect may be obtained. Examples of the acid anhydride include acarboxylic anhydride such as succinic anhydride, glutaric anhydride ormaleic anhydride, a disulfonic anhydride such as ethanedisulfonicanhydride or propanedisulfonic anhydride or an anhydride of a carboxylicacid and a sulfonic acid such as sulfobenzoic anhydride, sulfopropionicanhydride or sulfobutyric anhydride. Only one kind or a mixture of aplurality of kinds selected from them may be used. Among them, thesolvent more preferably includes succinic anhydride or sulfobenzoicanhydride, because a sufficient effect may be obtained.

For example, the intrinsic viscosity of the solvent is preferably 10.0mPa·s or less at 25° C. It is because the dissociation property of theelectrolyte salt and ion mobility may be secured. The intrinsicviscosity in a state in which the electrolyte salt is dissolved in thesovent (that is, the intrinsic viscosity of the electrolytic solution)is also preferably 10.0 mPa·s or less at 25° C. because of the samereason.

The electrolyte salt includes one kind or two or more kinds of lightmetal salts such as a lithium salt. Examples of the lithium salt includelithium hexafluorophosphate (LiPF₆), lithium tetrafluoroborate (LiBF₄),lithium perchlorate (LiClO₄), lithium hexafluoroarsenate (LiAsF₆),lithium tetraphenyl borate (LiB(C₆H₅)₄), lithium methanesulfonate(LiCH₃SO₃), lithium trifluoromethanesulfonate (LiCF₃SO₃), lithiumtetrachloroaluminate (LiAlCl₄), lithium hexafluorosilicate (Li₂SiF₆),lithium chloride (LiCl), lithium bromide (LiBr) and the like. Only onekind or a mixture of a plurality of kinds selected from them may beused. Among them, at least one kind selected from the group consistingof lithium hexafluorophosphate, lithium tetrafluoroborate, lithiumperchlorate and lithium hexafluoroarsenate is preferable, and inparticular, lithium hexafluorophosphate is more preferable, because theresistance of the electrolytic solution declines, so sufficient chemicalstability may be obtained. Moreover, a combination of lithiumhexafluorophosphate and lithium tetrafluoroborate is preferable, becausethe chemical stability of the electrolytic solution is further improved.

Moreover, the electrolyte salt preferably includes a compoundrepresented by Chemical Formula 28, because a higher effect may beobtained. As the compound represented by Chemical Formula 28, forexample, a compound represented by Chemical Formula 29 is cited.

where Z61 represents a Group 1A element or a Group 2A element in theshort form of the periodic table of the elements, or aluminum, M61represents phosphorus or boron, R61 represents a halogen group, an alkylgroup, a halogenated alkyl group, a aryl group or a halogenated arylgroup, X61 and X62 each represent oxygen or sulfur, Y61 represents—OC—R62-CO—, —OC—C(R63)(R64)- or —OC—CO—, in which R62 represents analkylene group, a halogenated alkylene group, an arylene group or ahalogenated arylene group, R63 and R64 each represent an alkyl group, ahalogenated alkyl group, an aryl group or a halogenated aryl group, anda6 is an integer of 1 to 4, b6 is an integer of 0 to 8, and c6, d6, m6and n6 each are an integer of 1 to 3.

where Z71 represents a Group 1A element or a Group 2A element in theshort form of the periodic table of the elements, or aluminum, M71represents phosphorus or boron, R71 represents a halogen group, Y71represents —OC—R72-CO—, —OC—C(R73)(R74)- or —OC—CO—, in which R72represents an alkylene group, a halogenated alkylene group, an arylenegroup or a halogenated arylene group, and R73 and R74 each represent analkyl group, a halogenated alkyl group, an aryl group or a halogenatedaryl group, and a7 is an integer of 1 to 4, b7 is an integer of 0, 2 or4, and c7, d7, m7 and n7 each are an integer of 1 to 3.

In addition, X61 and X62 represented by Chemical Formula 28 may be thesame as or different from each other. The same holds for R62 and R63represented by Chemical Formula 28 and R73 and R74 represented byChemical Formula 29.

Specific examples of the compound represented by Chemical Formula 29include compounds represented by Chemical Formulas 30(1) to 30(6). Onlyone kind or a mixture of a plurality of kinds selected from them may beused. Among them, the compound represented by Chemical Formula 30(6) ispreferable. It is because in the case where the compound represented byChemical Formula 30(6) is used together with the above-described lithiumhexafluorophosphate, a higher effect may be obtained. As long as thecompound has a composition represented by Chemical Formula 29, thecompound is not limited to the compounds represented by Chemical Formula30, and as long as the compound has a composition represented byChemical Formula 28, the compound is not limited to the compoundsrepresented by Chemical Formulas 29 and 30.

Moreover, the electrolyte salt preferably includes at least one kindselected from the group consisting of compounds represented by ChemicalFormulas 31, 32 and 33. It is because in the case where at least onekind selected from them is used together with the above-describedlithium hexafluorophosphate, a higher effect may be obtained. Inaddition, m and n represented by Chemical Formula 31 may be the same asor different from each other. The same holds for p, q and r representedby Chemical Formula 33.LiN(C_(m)F_(2m+1)SO₂)(C_(n)F_(2n+1)SO₂)  Chemical Formula 31

where m and n each are an integer of 1 or more.

where R81 represents a straight-chain or branched perfluoroalkylenegroup having 2 to 4 carbon atoms.LiC(C_(p)F_(2p+1)SO₂)(C_(q)F_(2q+1)SO₂)(C_(r)F_(2r+1)SO₂)  ChemicalFormula 33

where p, q and r each are an integer of 1 or more.

Specific examples of the chain compound represented by Chemical Formula31 include lithium bis(trifluoromethanesulfonyl)imide (LiN(CF₃SO₂)₂),lithium bis(pentafluoroethanesulfonyl)imide (LiN(C₂F₅SO₂)₂), lithium(trifluoromethanesulfonyl)(pentafluoroethanesulfonyl)imide(LiN(CF₃SO₂)(C₂F₅SO₂)), lithium(trifluoromethanesulfonyl)(heptafluoropropanesulfonyl)imide(LiN(CF₃SO₂)(C₃F₇SO₂)), lithium(trifluoromethanesulfonyl)(nonafluorobutanesulfonyl)imide(LiN(CF₃SO₂)(C₄F₉SO₂)) and the like. Only one kind or a mixture of aplurality of kinds selected from them may be used.

Specific examples of the cyclic compound represented by Chemical Formula32 include compounds represented by Chemical Formula 34. Morespecifically, lithium 1,2-perfluoroethanedisulfonylimide in ChemicalFormula 34(1), lithium 1,3-perfluoropropanedisulfonylimide in ChemicalFormula 34(2), lithium 1,3-perfluorobutanedisulfonylimide in ChemicalFormula 34(3), lithium 1,4-perfluorobutanedisulfonylimide in ChemicalFormula 34(4) and the like are cited. Only one kind or a mixture of aplurality of kinds selected from them may be used. Among them, lithium1,3-perfluoropropanedisulfonylimide is preferable, because a sufficienteffect may be obtained.

As a specific example of the chain compound represented by ChemicalFormula 33, lithium tris(trifluoromethanesulfonyl)methide (LiC(CF₃SO₂)₃)or the like is cited.

The content of the electrolyte salt is preferably within a range from0.3 mol/kg to 3.0 mol/kg both inclusive relative to the solvent. Whenthe content of the electrolyte salt is out of the range, ionicconductivity is extremely reduced, so it may be difficult to obtainsufficient capacity characteristics or the like in the electrochemicaldevice including the electrolytic solution.

In the electrolytic solution, the solvent includes at least one kindselected from the group consisting of the cyclic carbonate representedby Chemical Formula 11 which includes a halogen and the chain carbonaterepresented by Chemical Formula 12 which includes a halogen as the mainsolvent, and at least one kind selected from the group consisting of thecompounds represented by Chemical Formulas 13, 14 and 15 as the subsolvent, so compared to the case where the electrolytic solution doesnot include both of the main solvent and the sub solvent, chemicalstability is improved. Thereby, in the case where the electrolyticsolution is used in an electrochemical device such as a battery, theelectrolytic solution is able to contribute to improvement inhigh-temperature characteristics such as storage characteristics. Inthis case, when the content of the sub solvent (the compoundsrepresented by Chemical Formulas 13, 14 and 16) in the solvent is withina range from 0.001 wt % to 10 wt % both inclusive, a sufficient effectmay be obtained, and when the content is within a range from 0.001 wt %to 1 wt %, more specifically within a range from 0.1 wt % to 1 wt %, ahigher effect may be obtained.

In particular, when the solvent includes the compound represented byChemical Formula 26, a higher effect may be obtained.

Moreover, when the solvent includes the cyclic carbonate including anunsaturated bond, a sultone or an acid anhydride, a higher effect may beobtained.

Further, when the electrolyte salt includes lithium hexafluorophosphate,lithium tetrafluoroborate, lithium perchlorate or lithiumhexafluoroarsenate, the compound represented by Chemical Formula 28, orat least one kind selected from the group consisting of the compoundsrepresented by Chemical Formulas 31, 32 and 33, a higher effect may beobtained.

Next, application examples of the above-described electrolytic solutionwill be described below. As an example of the electrochemical device, abattery is cited, and the electrolytic solution is used in a battery asbelow.

(First Battery)

FIG. 1 shows a sectional view of a first battery. In this battery, thecapacity of an anode is represented by a capacity component based oninsertion and extraction of lithium as an electrode reactant, and thebattery is a so-called a lithium-ion secondary battery.

The battery includes a spirally wound electrode body 20 which includes acathode 21 and an anode 22 spirally wound with a separator 23 in betweenand a pair of insulating plates 12 and 13 in a substantially hollowcylindrical-shaped battery can 11. The battery can 11 is made of, forexample, nickel (Ni)-plated iron (Fe). An end portion of the battery can11 is closed, and the other end portion thereof is opened. The pair ofinsulating plates 12 and 13 are arranged so that the spirally woundelectrode body 20 is sandwiched therebetween, and the pair of insulatingplates 12 and 13 extends in a direction perpendicular to a peripheralwinding surface. A battery configuration using the battery can 11 iscalled a so-called cylindrical type.

In the opened end portion of the battery can 11, a battery cover 14, anda safety valve mechanism 15 and a positive temperature coefficientdevice (PTC device) 16 arranged inside the battery cover 14 are mountedby caulking by a gasket 17, and the interior of the battery can 11 issealed. The battery cover 14 is made of, for example, the same materialas that of the battery can 11. The safety valve mechanism 15 iselectrically connected to the battery cover 14 through the PTC device16. In the safety valve mechanism 15, when an internal pressure in thebattery increases to a certain extent or higher due to an internal shortcircuit or external application of heat, a disk plate 15A is flipped soas to disconnect the electrical connection between the battery cover 14and the spirally wound electrode body 20. When a temperature rises, thePTC device 16 limits a current by an increased resistance to preventabnormal heat generation caused by a large current. The gasket 17 ismade of, for example, an insulating material, and its surface is coatedwith asphalt.

A center pin 24 is inserted into the center of the spirally woundelectrode body 20. In the spirally wound electrode body 20, a cathodelead 25 made of aluminum or the like is connected to the cathode 21, andan anode lead 26 made of nickel or the like is connected to the anode22. The cathode lead 25 is welded to the safety valve mechanism 15 so asto be electrically connected to the battery cover 14, and the anode lead26 is welded to the battery can 11 so as to be electrically connected tothe battery can 11.

FIG. 2 shows an enlarged view of a part of the spirally wound electrodebody 20 shown in FIG. 1. The cathode 21 is formed by arranging a cathodeactive material layer 21B on both sides of a cathode current collector21A having a pair of facing surfaces. In FIG. 2, the cathode activematerial layer 21B is arranged on both sides of the cathode currentcollector 21A; however, the cathode active material layer 21B may bearranged on one side of the cathode current collector 21A. The cathodecurrent collector 21A is made of, for example, a metal material such asaluminum, nickel or stainless. The cathode active material layer 21Bincludes one kind or two or more kinds of cathode materials capable ofinserting and extracting lithium as an electrode reactant. The cathodeactive material layer 21B may include an electrical conductor, a binderor the like, if necessary.

As the cathode material capable of inserting and extracting lithium, forexample, lithium cobalt oxide, lithium nickel oxide, a solid solutionincluding lithium cobalt oxide and lithium nickel oxide(Li(Ni_(x)Co_(y)Mn_(z))O₂; the values of x, y and z are 0<x<1, 0<y<1 and0<z<1, and x+y+z=1), lithium complex oxide such as lithium manganeseoxide (LiMn₂O₄) with a spinel structure or a solid solution thereof(Li(Mn_(2-v)Ni_(v))O₄; the value of v is v<2), or a phosphate compoundwith an olivine structure such as lithium iron phosphate (LiFePO₄) ispreferable, because a high energy density may be obtained. Moreover,examples of the above-described cathode material include oxides such astitanium oxide, vanadium oxide and manganese dioxide, bisulfides such asiron bisulfide, titanium bisulfide and molybdenum sulfide, sulfur, andconductive polymers such as polyaniline and polythiophene.

The anode 22 is formed by arranging an anode active material layer 22Bon both sides of an anode current collector 22A having a pair of facingsurfaces. The anode active material layer 22B is arranged on both sidesof the anode current collector 22A; however, the anode active materiallayer 22B may be arranged on one side of the anode current collector22A. The anode current collector 22A is preferably made of a metalmaterial having good electrochemical stability, electrical conductivityand mechanical strength. Examples of the metal material include copper(Cu), nickel, stainless and the like. Among them, as the metal material,copper is preferable, because high electrical conductivity may beobtained.

In particular, as the metal material of which the anode currentcollector 22A is made, a metal material including one kind or two ormore kinds of metal elements which do not form an intermetallic compoundwith lithium is preferable. When the metal elements form anintermetallic compound with lithium, the influence of a stress due toswelling and shrinkage of the anode active material layer 22B duringcharge and discharge causes a fracture of the anode active materiallayer 22B, so the current collecting property easily declines, and theanode active martial layer 22B is easily peeled. Examples of the metalelements include copper, nickel, titanium (Ti), iron, chromium (Cr) andthe like.

The anode active material layer 22B includes one kind or two or morekinds of anode material capable of inserting and extracting lithium asanode active materials. The anode active material layer 22B may includean electrical conductor, a binder or the like, if necessary. The chargecapacity of the anode material capable of inserting and extractinglithium is preferably larger than a charge capacity by the cathodeactive material.

As the anode material capable of inserting and extracting lithium, forexample, a carbon material is cited. Examples of such a carbon materialinclude graphitizable carbon, non-graphitizable carbon with a (002)plane interval of 0.37 nm or more, graphite with a (002) plane intervalof 0.34 nm or less, and the like. More specifically, kinds of pyrolyticcarbon, kinds of coke, kinds of graphite, glass-like carbon fibers,fired organic polymer compound bodies, carbon fibers, activated carbon,kinds of carbon black and the like are cited. Among them, kinds of cokeinclude pitch coke, needle coke, petroleum coke and so on, and the firedorganic polymer compound bodies are polymers such as a phenolic resinand a furan resin which are carbonized by firing at an adequatetemperature. These carbon materials are preferable, because a change ina crystal structure according to insertion and extraction of lithium isvery small, so a high energy density may be obtained, and superior cyclecharacteristics may be obtained, and the carbon materials also functionas electrical conductors.

As the anode material capable of inserting and extracting lithium, amaterial capable of inserting and extracting lithium and including atleast one kind selected from the group consisting of metal elements andmetalloid elements as an element is cited. Such an anode material ispreferable, because a high energy density may be obtained. The anodematerial may be a simple substance, an alloy or a compound of a metalelement or a metalloid element, or a material including a phaseincluding one kind or two or more kinds of them at least in part. In thepresent invention, the alloy means an alloy including two or more kindsof metal elements as well as an alloy including one or more kinds ofmetal elements and one or more kinds of metalloid elements. Moreover,the alloy may include a non-metal element. As the texture of the alloy,a solid solution, a eutectic (eutectic mixture), an intermetalliccompound or the coexistence of two or more kinds selected from them iscited.

As the metal element or the metalloid element included in the anodematerial, for example, magnesium (Mg), boron, aluminum, gallium (Ga),indium (In), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), bismuth(Bi), cadmium (Cd), silver (Ag), zinc (Zn), hafnium (Hf), zirconium(Zr), yttrium (Y), palladium (Pd), platinum (Pt) or the like is cited.They may be crystalline or amorphous. As an alloy or a compound of anyone of the metal elements and the metalloid elements, for example, analloy or a compound represented by a chemical formula ofMa_(s)Mb_(t)Li_(u), (the values of s, t and u are s>0, t≥0 and u≥0,respectively) or Ma_(p)Mc_(q)Md_(r) (the values of p, q and r are p>0,q>0 and r≥0, respectively) or the like is cited. In the chemicalformulas, Ma represents at least one kind selected from metal elementsand metalloid elements capable of forming an alloy with lithium, and Mbrepresents at least one kind selected from metal elements and metalloidelements except for lithium and Ma. Moreover, Mc represents at least onekind of non-metal element, and Md represents at least one kind selectedfrom metal elements and metalloid elements except for Ma.

As the anode material made of a metal element or a metalloid elementcapable of forming an alloy with lithium, an anode material including atleast one kind selected from the group consisting of Group 4B metalelements and Group 4B metalloid elements in the short form of theperiodic table of the elements as an element is preferable, and amaterial including at least one kind selected from silicon and tin isspecifically preferable. It is because the material has a largecapability to insert and extract lithium, so a high energy density maybe obtained.

As the material including at least one kind selected from the groupconsisting of silicon and tin, for example, at least one kind selectedfrom the group consisting of the simple substance, alloys and compoundsof silicon and the simple substance, alloys and compounds of tin iscited. More specifically, a material including the simple substance, analloy or a compound of silicon, the simple substance, an alloy or acompound of tin, or a material including a phase of one kind or two ormore kinds selected from them at least in a part thereof is cited. Onlyone kind or a mixture of a plurality of kinds selected from them may beused.

As an alloy of silicon, for example, an alloy including at least onekind selected from the group consisting of tin, nickel, copper, iron,cobalt (Co), manganese (Mn), zinc, indium, silver, titanium, germanium,bismuth, antimony (Sb) and chromium as a second element in addition tosilicon is cited. As an alloy of tin, for example, an alloy including atleast one kind selected from the group consisting of silicon, nickel,copper, iron, cobalt, manganese, zinc, indium, silver, titanium,germanium, bismuth, antimony and chromium as a second element inaddition to tin is cited.

As a compound of silicon or a compound of tin, for example, a compoundincluding oxygen or carbon is cited, and in addition to silicon or tin,the compound may include the above-described second element.

As the alloy or the compound of silicon or the ally or the compound oftin, for example, SiB₄, SiB₆, Mg₂Si, Ni₂Si, TiSi₂, MoSi₂, CoSi₂, NiSi₂,CaSi₂, CrSi₂, Cu₅Si, FeSi₂, MnSi₂, NbSi₂, TaSi₂, VSi₂, WSi₂, ZnSi₂, SiC,Si₃N₄, Si₂N₂O, SiO_(v) (0<v≤2), LiSiO, Mg₂Sn, SnSiO₃, LiSnO, SnO_(w)(0<w≤2) or the like is cited.

In particular, as the material including at least one kind selected fromthe group consisting of silicon and tin as an element, a materialincluding a second element and a third element in addition to tin as afirst element is preferable. The second element includes at least onekind selected from the group consisting of cobalt, iron, magnesium,titanium, vanadium (V), chromium, manganese, nickel, copper, zinc,gallium, zirconium, niobium (Nb), molybdenum (Mo), silver, indium,cerium (Ce), hafnium, tantalum (Ta), tungsten (W), bismuth and silicon.The third element includes at least one kind selected from the groupconsisting of boron, carbon, aluminum and phosphorus. It is because whenthe second element and the third element are included, cyclecharacteristics are improved.

Among them, a CoSnC-containing material in which tin, cobalt and carbonare included as elements, and the carbon content is within a range from9.9 wt % to 29.7 wt % both inclusive, and the ratio of cobalt to thetotal of tin and cobalt (Co/(Sn+Co)) is within a range from 30 wt % to70 wt % both inclusive is preferable, because a high energy density maybe obtained in such a composition range.

The CoSnC-containing material may include any other element, ifnecessary. As the element, for example, silicon, iron, nickel, chromium,indium, niobium, germanium, titanium, molybdenum, aluminum, phosphorus,gallium, bismuth or the like is preferable, and two or more kindsselected from them may be included. It is because a higher effect may beobtained.

The CoSnC-containing material includes a phase including tin, cobalt andcarbon, and the phase preferably has a low crystalline structure or anamorphous structure. Moreover, in the CoSnC-containing material, atleast a part of carbon as an element is preferably bonded to a metalelement or a metalloid element as another element. It is becausecohesion or crystallization of tin or the like is prevented.

As a measuring method for checking the bonding state of an element, forexample, X-ray photoelectron spectroscopy (XPS) is used. In the XPS, thepeak of the 1s orbit (C1s) of carbon in the case of graphite is observedat 284.5 eV in an apparatus in which energy calibration is performed sothat the peak of the 4f orbit (Au4f) of a gold atom is observed at 84.0eV. Moreover, the peak of C1s of the surface contamination carbon isobserved at 284.8 eV. On the other hand, in the case where the chargedensity of the carbon element increases, for example, in the case wherecarbon is bonded to a metal element or a metalloid element, the peak ofC1s is observed in a region lower than 284.5 eV. In other words, in thecase where the peak of the composite wave of C1s obtained in theCoSnC-containing material is observed in a region lower than 284.5 eV,at least a part of carbon included in the CoSnC-containing material isbonded to the metal element or the metalloid element which is anotherelement.

Moreover, in the XPS measurement, for example, the peak of C1s is usedto correct the energy axis of a spectrum. In general, surfacecontamination carbon exists on a material surface, so the peak of C1s ofthe surface contamination carbon is fixed at 284.8 eV, and the peak isused as an energy reference. In the XPS measurement, the waveform of thepeak of C1s is obtained as a form including the peak of the surfacecontamination carbon and the peak of carbon in the CoSnC-containingmaterial, so the peak of the surface contamination carbon and the peakof the carbon in the CoSnC-containing material are separated byanalyzing the waveform through the use of, for example, commerciallyavailable software. In the analysis of the waveform, the position of amain peak existing on a lowest binding energy side is used as an energyreference (284.8 eV).

Further, as the anode material capable of inserting and extractinglithium, for example, a metal oxide or a polymer compound capable ofinserting and extracting lithium or the like is cited. As the metaloxide, for example, iron oxide, ruthenium oxide, molybdenum oxide or thelike is cited, and as the polymer compound, for example, polyacetylene,polyaniline, polypyrrole or the like is cited.

A combination of the above-described anode materials capable ofinserting and extracting lithium may be used.

As the electrical conductor, for example, a carbon material such asgraphite, carbon black or ketjen black is cited. Only one kind or amixture of a plurality of kinds selected from them may be used. As longas the electrical conductor is a material having electricalconductivity, any metal material or any conductive polymer may be used.

As the binder, for example, synthetic rubber such as styrenebutadiene-based rubber, fluorine-based rubber or ethylene propylenediene or a polymer material such as polyvinylidene fluoride is cited.Only one kind or a mixture of a plurality of kinds selected from themmay be used. However, as shown in FIG. 1, in the case where the cathode21 and the anode 22 are spirally wound, styrene butadiene-based rubberor fluorine-based rubber which has high flexibility is preferably used.

The separator 23 isolates between the cathode 21 and the anode 22 sothat lithium ions pass therethrough while preventing a short circuit ofa current due to contact between the cathode 21 and the anode 22. Theseparator 23 is made of, for example, a porous film of a synthetic resinsuch as polytetrafluoroethylene, polypropylene or polyethylene, or aporous ceramic film, and the separator 23 may have a configuration inwhich two or more kinds of the porous films are laminated. Among them, aporous film made of polyolefin is preferable, because a short-circuitpreventing effect is superior, and the safety of the battery by ashutdown effect can be improved. In particular, polyethylene ispreferable, because a shutdown effect may be obtained within a rangefrom 100° C. to 160° C. both inclusive, and electrochemical stability issuperior. Moreover, polypropylene is preferable, and any other resinhaving chemical stability may be used by copolymerizing or blending withpolyethylene or polypropylene.

The separator 23 is impregnated with the above-described electrolyticsolution as a liquid electrolyte, because while maintaining cyclecharacteristics, storage characteristics may be improved.

The secondary battery is manufactured by the following steps, forexample.

At first, the cathode active material layer 21B is formed on both sidesof the cathode current collector 21A to form the cathode 21. The cathodeactive material layer 21B is formed by the following steps. A cathodemixture formed by mixing cathode active material powder, the electricalconductor and the binder is dispersed in a solvent to form paste-formcathode mixture slurry, and the cathode mixture slurry is applied to thecathode current collector 21A, and the cathode mixture slurry is driedand compression molded, thereby the cathode active material layer 21B isformed. Moreover, for example, by the same steps as those in the case ofthe cathode 21, the anode 22 is formed by forming the anode activematerial layer 22B on the both sides of the anode current collector 22A.

Next, the cathode lead 25 is attached to the cathode current collector21A by welding, and the anode lead 26 is attached to the anode currentcollector 22A by welding. Then, the cathode 21 and the anode 22 arespirally wound with the separator 23 in between so as to form thespirally wound electrode body 20, and an end of the cathode lead 25 iswelded to the safety valve mechanism 15, and an end of the anode lead 26is welded to the battery can 11. Next, the spirally wound electrode body20 is sandwiched between the pair of insulating plates 12 and 13, andthey are contained in the battery can 11. Next, the electrolyticsolution is injected into the battery can 11 so as to impregnate theseparator 23 with the electrolytic solution. Finally, the battery cover14, the safety valve mechanism 15 and the PTC device 16 are fixed in anopened end portion of the battery can 11 by caulking by the gasket 17.Thereby, the secondary battery shown in FIGS. 1 and 2 is completed.

When the secondary battery is charged, lithium ions are extracted fromthe cathode 21, and are inserted into the anode 22 through theelectrolytic solution. On the other hand, when the secondary battery isdischarged, the lithium ions are extracted from the anode 22 and areinserted into the cathode 21 through the electrolytic solution.

In the cylindrical secondary battery, in the case where the capacity ofthe anode is represented by a capacity component based on insertion andextraction of lithium, the above-described electrolytic solution isincluded, so the decomposition of the electrolytic solution isprevented. Therefore, high-temperature characteristics such as storagecharacteristics may be improved. Other effects relating to the secondarybattery are the same as those in the above-described electrolyticsolution.

Next, second and third batteries will be described below, and likecomponents are denoted by like numerals as of the first battery, andwill not be further described.

(Second Battery)

The second battery has the same configuration, functions and effects asthose of the first battery, except for the configuration of an anode 22is different, and the second battery is manufactured by the same methodas that of the first battery.

The anode 22 has a configuration in which the anode active materiallayer 22B is arranged on both sides of the anode current collector 22Aas in the case of the first battery. As the anode active material, theanode active material layer 22B includes, for example, a materialincluding tin or silicon as an element. More specifically, for example,the anode active material includes the simple substance, an alloy or acompound of tin, or the simple substance, an alloy or a compound ofsilicon, and the anode active material may include two or more kindsselected from them.

The anode active material layer 22B is formed by, for example, avapor-phase method, a liquid-phase method, a spraying method or a firingmethod, or a combination of two or more methods selected from them, andthe anode active material layer 22B and the anode current collector 22Aare preferably alloyed in at least a part of an interface therebetween.More specifically, in the interface, an element of the anode currentcollector 22A is preferably diffused into the anode active materiallayer 22B, or an element of the anode active material layer 22B ispreferably diffused into the anode current collector 22A, or they arepreferably diffused into each other, because a fracture of the anodeactive material layer 22B due to swelling and shrinkage thereofaccording to charge and discharge may be inhibited, and the electronicconductivity between the anode active material layer 22B and the anodecurrent collector 22A may be improved.

As the vapor-phase method, for example, a physical deposition method ora chemical deposition method, more specifically, a vacuum depositionmethod, a sputtering method, an ion plating method, a laser ablationmethod, a thermal CVD (chemical vapor deposition) method, a plasmachemical vapor deposition method or the like is cited. As theliquid-phase method, a known technique such as electrolytic plating orelectroless plating may be used. In the firing method, for example, aparticulate anode active material is mixed with a binder or the like toform a mixture, and the mixture is applied by dispersing the mixture ina solvent, and then the mixture is heated at a higher temperature thanthe melting point of the binder or the like. As the firing method, aknown technique such as, for example, an atmosphere firing method, areaction firing method or a hot press firing method is cited.

(Third Battery)

In a third battery, the capacity of the anode 22 is represented by acapacity component based on precipitation and dissolution of lithium,and the third battery is a so-called lithium metal secondary battery.The secondary battery has the same configuration as that of the firstbattery, except that the anode active material layer 22B is made oflithium metal, and the secondary battery is manufactured by the samemethod as that of the first battery.

The secondary battery uses lithium metal as the anode active material,so a higher energy density may be obtained. The anode active materiallayer 22B may exist at the time of assembling, or may not exist at thetime of assembling, and may be formed of lithium metal precipitated atthe time of charge. Moreover, the anode active material layer 22B may beused also as a current collector, thereby the anode current collector22A may be removed.

When the secondary battery is charged, lithium ions are extracted fromthe cathode 21, and the lithium ions are precipitated on the surface ofthe anode current collector 22A as lithium metal through theelectrolytic solution. When the secondary battery is discharged, thelithium metal is dissolved from the anode active material layer 22B aslithium ions, and the lithium ions are inserted into the cathode 21through the electrolytic solution.

In the cylindrical secondary battery, in the case where the capacity ofthe anode 22 is represented by a capacity component based onprecipitation and dissolution of lithium, the above-describedelectrolytic solution is included, so the high-temperaturecharacteristics such as the storage characteristics may be improved.Other effects relating to the secondary battery are the same as those inthe first battery.

(Fourth Battery)

FIG. 3 shows an exploded perspective view of a fourth battery. In thebattery, a spirally wound electrode body 30 to which a cathode lead 31and an anode lead 32 are attached is contained in film-shaped packagemembers 40, and the configuration of the battery is a so-called laminatefilm type.

The cathode lead 31 and the anode lead 32 are drawn, for example, fromthe interiors of the package members 40 to outside in the samedirection. The cathode lead 31 is made of, for example, a metal materialsuch as aluminum, and the anode lead 32 are made of, for example, ametal material such as copper, nickel or stainless. The metal materialsof which the cathode lead 31 and the anode lead 32 are made each have asheet shape or a mesh shape.

The package members 40 are made of, for example, a rectangular aluminumlaminate film including a nylon film, aluminum foil and a polyethylenefilm which are bonded in this order. The package members 40 are arrangedso that the polyethylene film of each of the package members 40 facesthe spirally wound electrode body 30, and edge portions of the packagemembers 40 are adhered to each other by fusion bonding or an adhesive.An adhesive film 41 is inserted between the package members 40 and thecathode lead 31 and the anode lead 32 for preventing the entry ofoutside air. The adhesive film 41 is made of, for example, a materialhaving adhesion to the cathode lead 31 and the anode lead 32, forexample, a polyolefin resin such as polyethylene, polypropylene,modified polyethylene or modified polypropylene.

In addition, the package members 40 may be made of a laminate film withany other configuration, a polymer film such as polypropylene or a metalfilm instead of the above-described three-layer aluminum laminate film.

FIG. 4 shows a sectional view of the spirally wound electrode body 30taken along a line I-I of FIG. 3. The spirally wound electrode body 30is formed by laminating a cathode 33 and an anode 34 with a separator 35and an electrolyte 36 in between, and then spirally winding them, and anoutermost portion of the spirally wound electrode body 30 is protectedwith a protective tape 37.

The cathode 33 is formed by arranging a cathode active material layer33B on both sides of a cathode current collector 33A. The anode 34 isformed by arranging an anode active material layer 34B on both sides ofan anode current collector 34A, and the anode 34 is arranged so that theanode active material layer 34B faces the cathode active material layer33B. The configurations of the cathode current collector 33A, thecathode active material layer 33B, the anode current collector 34A, theanode active material layer 34B and the separator 35 are the same asthose of the cathode current collector 21A, the cathode active materiallayer 21B, the anode current collector 22A, the anode active materiallayer 22B and the separator 23 in the above-described first, second andthird batteries, respectively.

The electrolyte 36 includes the above-described electrolytic solutionand a polymer compound holding the electrolytic solution, and is aso-called gel electrolyte. The gel electrolyte is preferable, becausethe gel electrolyte is able to obtain high ionic conductivity (forexample, 1 mS/cm or over at room temperature), and leakage of anelectrolyte from the battery is prevented.

Examples of the polymer compound include polyacrylonitrile,polyvinylidene fluoride, a copolymer of polyvinylidene fluoride andpolyhexafluoropyrene, polytetrafluoroethylene, polyhexafluoropropylene,polyethylene oxide, polypropylene oxide, polyphosphazene, polysiloxane,polyvinyl acetate, polyvinyl alcohol, polymethyl methacrylate,polyacrylic acids, polymethacrylic acids, styrene-butadiene rubber,nitrile-butadiene rubber, polystyrene, polycarbonate and the like. Onekind or a mixture of a plurality of kinds selected from them may beused. In particular, in terms of electrochemical stability,polyacrylonitrile, polyvinylidene fluoride, polyhexafluoropropylene,polyethylene oxide or the like is preferably used. The content of thepolymer compound in the electrolytic solution depends on compatibilitybetween them, but is preferably within a range from 5 wt % to 50 wt %both inclusive.

The content of the electrolyte salt is the same as that in the case ofthe above-described first, second and third batteries. The solvent inthis case has a wide concept including not only a liquid solvent butalso a solvent having ionic conductivity capable of dissociating theelectrolyte salt. Therefore, in the case where a polymer compound havingionic conductivity is used, the polymer compound is included in theconcept of the solvent.

In addition, as the electrolyte 36, instead of an electrolyte in whichthe polymer compound holds the electrolytic solution, the electrolyticsolution may be used as it is. In this case, the separator 35 isimpregnated with the electrolytic solution.

The secondary battery may be manufactured by the following three kindsof manufacturing methods, for example.

In a first manufacturing method, by the same steps as those in themethod of manufacturing the first battery, at first, the cathode activematerial layer 33B are formed on both sides of the cathode currentcollector 33A so as to form the cathode 33. Moreover, for example, bythe same steps as those in the method of manufacturing the firstbattery, the anode active material layer 34B is formed on both sides ofthe anode current collector 34A so as to form the anode 34.

Next, the gel electrolyte 36 is formed by preparing a precursor solutionincluding the electrolytic solution, the polymer compound and a solvent,applying the precursor solution to the cathode 33 and the anode 34, andvolatilizing the solvent. Next, the cathode lead 31 and the anode lead32 are attached to the cathode current collector 33A and the anodecurrent collector 34A, respectively. Next, after the cathode 33 on whichthe electrolyte 36 is formed and the anode 34 on which the electrolyte36 is formed are laminated with the separator 35 in between to form alaminate, the laminate is spirally wound in a longitudinal direction,and the protective tape 37 is bonded to an outermost portion of thelaminate so as to form the spirally wound electrode body 30. Then, forexample, the spirally wound electrode body 30 is sandwiched between twofilm-shaped package members 40, and edge portions of the package members40 are adhered to each other by thermal fusion bonding or the like toseal the spirally wound electrode body 30 in the package members 40. Atthis time, the adhesive film 41 is inserted between the cathode lead 31and the anode lead 32, and the package members 40. Thereby, thesecondary battery shown in FIGS. 3 and 4 is completed.

In a second manufacturing method, at first, after the cathode lead 31and the anode lead 32 are attached to the cathode 33 and the anode 34,respectively, the cathode 33 and the anode 34 are laminated with theseparator 35 in between to form a laminate, and the laminate is spirallywound, and the protective tape 37 is bonded to an outermost portion ofthe spirally wound laminate so as to form a spirally wound body as aprecursor body of the spirally wound electrode body 30. Next, thespirally wound body is sandwiched between two film-shaped packagemembers 40, and the edge portions of the package members 40 except foredge portions on one side are adhered by thermal fusion bonding or thelike to form a pouched package, thereby the spirally wound body iscontained in the package members 40. An electrolytic composition whichincludes the electrolytic solution, monomers as materials of a polymercompound and a polymerization initiator and, if necessary, any othermaterial such as a polymerization inhibitor is prepared, and thecomposition is injected in the package members 40, and then an openedportion of the package members 40 is sealed by thermal fusion bonding orthe like. Finally, the monomers are polymerized by applying heat to formthe polymer compound, thereby the gel electrolyte 36 is formed. Thus,the secondary battery is completed.

In a third manufacturing method, as in the case of the firstmanufacturing method, the spirally wound body is formed, and thespirally wound body is contained in the package members 40, except thatthe separator 35 with both sides coated with a polymer compound is used.As the polymer compound applied to the separator 35, for example, apolymer including vinylidene fluoride as a component, that is, ahomopolymer, a copolymer, a multicomponent copolymer, or the like iscited. More specifically, polyvinylidene fluoride, a binary copolymerincluding vinylidene fluoride and hexafluoropropylene as components, aternary copolymer including vinylidene fluoride, hexafluoropropylene andchlorotrifluoroethylene as components is cited. The polymer compound mayinclude one kind or two or more kinds of other polymer compounds inaddition to the above-described polymer including vinylidene fluoride asa component. Next, after the electrolytic solution is prepared, andinjected into the package members 40, an opened portion of the packagemembers 40 are sealed by thermal fusion bonding or the like. Finally,the package members 40 are heated while being weighted so that theseparator 35 is brought into close contact with the cathode 33 and theanode 34 with the polymer compound in between. Thereby, the polymercompound is impregnated with the electrolytic solution, and the polymercompound is gelatinized so as to form the electrolyte 36, so thesecondary battery is completed. In the third manufacturing method,compared to the first manufacturing method, swelling characteristics areimproved. Moreover, in the third manufacturing method, compared to thesecond manufacturing method, monomers as the materials of the polymercompound, the solvent or the like hardly remain in the electrolyte 36,and a step of forming the polymer compound is controlled well, sosufficient adhesion between the cathode 33 and anode 34, and theseparator 35 and the electrolyte 36 is obtained.

The functions and effects of the laminate type secondary battery are thesame as those in the first battery.

(Fifth Battery)

FIG. 5 shows a sectional view of a fifth battery. The battery ismanufactured by the following steps. A cathode 51 is bonded to a packagecan 54, and an anode 52 is contained in a package cup 55, and thepackage can 54 and the package cup 55 are laminated with a separator 53which is impregnated with the electrolytic solution in between, and thenthey are caulked by a gasket 56. A battery configuration using thepackage can 54 and the package cup 55 is called a so-called coin type.

The cathode 51 is formed by applying a cathode active material layer 51Bon one side of a cathode current collector 61A. The anode 52 is formedby applying an anode active material layer 52B on one side of the anodecurrent collector 52A. The configurations of the cathode currentcollector 61A, the cathode active material layer 52B, the anode currentcollector 52A, the anode active material layer 52B and the separator 53are the same as those of the cathode current collector 21A, the cathodeactive material layer 21B, the anode current collector 22A, the anodeactive material layer 22B and the separator 23 in the first, second andthird batteries, respectively.

The functions and effects of the coin type secondary battery are thesame as those in the first battery.

EXAMPLES

Specific examples of the invention will be described in detail below.

Example 1-1

A cylindrical secondary battery shown in FIGS. 1 and 2 was formedthrough the use of artificial graphite as an anode active material. Atthat time, the secondary battery was a lithium-ion secondary battery inwhich the capacity of the anode 22 was represented by a capacitycomponent based on insertion and extraction of lithium.

At first, the cathode 21 was formed. In this case, after lithiumcarbonate (Li₂CO₃) and cobalt carbonate (CoCO₃) were mixed at a molarratio of 0.5:1, the mixture was fired in air at 900° C. for 5 hours toobtain a lithium-cobalt complex oxide. Next, after 91 parts by weight ofthe lithium-cobalt complex oxide as a cathode active material, 6 partsby weight of graphite as an electrical conductor and 3 parts by weightof polyvinylidene fluoride as a binder were mixed to form a cathodemixture, the cathode mixture was dispersed in N-methyl-2-pyrrolidone toform paste-form cathode mixture slurry. Then, after the cathode mixtureslurry was uniformly applied to the cathode current collector 21A madeof strip-shaped aluminum foil (with a thickness of 20 μm), and wasdried, the cathode mixture slurry was compression molded by a rollerpress to form the cathode active material layer 21B. After that, thecathode lead 25 was attached to an end of the cathode current collector21A.

Next, the anode 22 was formed. In this case, 90 parts by weight ofgraphite powder as an anode active material and 10 parts by weight ofpolyvinylidene fluoride as a binder were mixed to form an anode mixture,and then the anode mixture was dispersed in N-methyl-2-pyrrolidone toform paste-form anode mixture slurry. Then, after the anode mixtureslurry was uniformly applied to the anode current collector 22A made ofstrip-shaped copper foil (with a thickness of 15 μm), and was dried, theanode mixture slurry was compression molded by a roller press to formthe anode active material layer 22B. After that, the anode lead 26 wasattached to an end of the anode current collector 22A.

Next, the electrolytic solution was prepared. In this case, at first,after ethylene carbonate (EC) and dimethyl carbonate (DMC) as mainsolvents were mixed at a weight ratio of30:70,4-fluoro-1,3-dioxolane-2-one (FEC) as the cyclic carbonaterepresented by Chemical Formula 11 which included a halogen as a mainsolvent and the compound represented by Chemical Formula 23 as thecompound represented by Chemical Formula 13 as a sub solvent were addedto the mixture to obtain a solvent. At that time, the content of FEC inthe solvent was 1 wt %, and the content of the compound represented byChemical Formula 23 was 0.1 wt %. The unit “wt %” means a value in thecase where the whole solvent including the main solvent and the subsolvent is 100 wt %, and hereinafter the meaning of “wt %” is the same.After that, lithium hexafluorophosphate (LiPF₆) as an electrolyte saltwas added to and dissolved in the solvent so that the concentration ofthe electrolyte salt in the electrolytic solution became 1 mol/kg.

Next, the separator 23 made of a microporous polypropylene film (with athickness of 25 μm) was prepared, and the anode 22, the separator 23,the cathode 21 and the separator 23 were laminated in this order to forma laminate, and then the laminate was spirally wound several times toform the spirally wound electrode body 20. Then, the spirally woundelectrode body 20 was sandwiched between a pair of insulating plates 12and 13, and the anode lead 26 was welded to the battery can 11, and thecathode lead 25 was welded to the safety valve mechanism 15, and thenthe spirally wound electrode body 20 was contained in the battery can 11made of nickel-plated iron. Finally, the electrolytic solution wasinjected into the battery can 11 by a decompression method so as to formthe cylindrical secondary battery.

Examples 1-2 to 1-4

Secondary batteries were formed by the same steps as those in Example1-1, except that instead of FEC, as the main solvent,trans-4,5-difluoro-1,3-dioxolane-2-one (t-DFEC: Example 1-2) orcis-4,5-difluoro-1,3-dioxolane-2-one (c-DFEC: Example 1-3) as the cycliccarbonate represented by Chemical Formula 11 which included a halogen,or bis(fluoromethyl) carbonate (DFDMC: Example 1-4) as the chaincarbonate represented by Chemical Formula 12 which included a halogenwas used.

Examples 1-5, 1-6

Secondary batteries were formed by the same steps as those in Example1-1, except that instead of the compound represented by Chemical Formula23 as the sub solvent, the compound represented by Chemical Formula 24as the compound represented by Chemical Formula 14 (Example 1-6) or thecompound represented by Chemical Formula 25 as the compound representedby Chemical Formula 15 (Example 1-6) was used.

Example 1-7

A secondary battery was formed by the same steps as those in Example1-1, except that as the sub solvent, the compound represented byChemical Formula 24 was added. At that time, the content of the compoundrepresented by Chemical Formula 23 in the solvent was 0.05 wt %, and thecontent of the compound represented by Chemical Formula 24 was 0.05 wt%.

Examples 1-8 to 1-11

Secondary batteries were formed by the same steps as those in Examples1-1 to 1-4, except that as an auxiliary solvent, the compoundrepresented by Chemical Formula 27 as the compound represented byChemical Formula 26 was added. At that time, the compound represented byChemical Formula 27 in the solvent was 0.01 wt %.

Comparative Example 1-1

A secondary battery was formed by the same steps as those in Example1-1, except that FEC as the main solvent and the compound represented byChemical Formula 23 as the sub solvent were not added.

Comparative Examples 1-2, 1-3

Secondary batteries were formed by the same steps as those in Examples1-1 and 1-2, except that the compound represented by Chemical Formula 23as the sub solvent was not added.

Comparative Example 1-4

A secondary battery was formed by the same steps as those in Example1-1, except that FEC as the main solvent was not added.

When the storage characteristics and the cycle characteristics of thesecondary batteries of Examples 1-1 to 1-11 and Comparative Examples 1-1to 1-4 were determined, results shown in Table 1 were obtained.

To determine the storage characteristics, the secondary batteries werestored by the following steps, and then the discharge capacity retentionratios (hereinafter referred to as “storage discharge capacity retentionratios”) of the secondary batteries were determined. At first, 2 cyclesof charge and discharge were performed in an atmosphere at 23° C., andthen the discharge capacity in the second cycle (the discharge capacitybefore storing) of each of the secondary batteries was determined. Next,after the secondary batteries which were charged again were stored for 1month in a constant temperature bath at 60° C., the secondary batterieswere discharged in an atmosphere at 23° C., and then the dischargecapacity in the third cycle (the discharge capacity after storing) ofeach of the secondary batteries was determined. Finally, the storagedischarge capacity retention ratio (%)=(discharge capacity afterstoring/discharge capacity before storing)×100 was determined bycalculation. As the conditions of 1 cycle of charge, after the secondarybatteries were charged at a constant current of 1 C until the batteryvoltage reached 4.2 V, the secondary batteries were charged at aconstant voltage of 4.2 V until the total charge time reached 2 hours.Moreover, as the conditions of 1 cycle of discharge, the secondarybatteries were discharged at a constant current of 0.5 C until thebattery voltage reached 3.0 V. The unit “C” represents a value showing acurrent condition, and “1 C” represents a current value at which thetheoretical capacity of the battery is fully discharged for 1 hour, and“0.5 C” represents a current value at which the theoretical capacity ofthe battery is fully discharged for 2 hours.

To determine the cycle characteristics, after the secondary batterieswere repeatedly charged and discharged by the following steps, thedischarge capacity retention ratios (hereinafter referred to as “cycledischarge capacity retention ratios”) of the secondary batteries weredetermined. At first, 2 cycles of charge and discharge were performed inan atmosphere at 23° C., and then the discharge capacity in the secondcycle of each of the secondary batteries was determined. Next, 102cycles of charge and discharge in total were performed in a constanttemperature bath at 60° C., and then the discharge capacity in the 102ndcycle of each of the secondary batteries was determined. Finally, thecycle discharge capacity retention ratio (%)=(discharge capacity in the102nd cycle/discharge capacity in the second cycle)×100 was determinedby calculation. The conditions of 1 cycle of charge and discharge werethe same as those in the case where the storage characteristics weredetermined.

In addition, the same steps and the same conditions as theabove-described steps and the above-described conditions were used todetermine the storage characteristics and the cycle characteristics ofsecondary batteries in the following examples and the followingcomparative examples.

TABLE 1 Anode active material: artificial graphite DISCHARGE CAPACITYSOLVENT RETENTION ELECTROLYTE AUXILIARY RATIO (%) SALT MAIN SOLVENT SUBSOLVENT SOLVENT STORAGE CYCLE EXAMPLE 1-1 LIPF₆ EC + DMC FEC CHEMICAL —86 81 EXAMPLE 1-2 1 mol/kg t-DFEC FORMULA 23 86 85 EXAMPLE 1-3 c-DFEC 8685 EXAMPLE 1-4 DFDMC 88 83 EXAMPLE 1-5 FEC CHEMICAL 86 81 FORMULA 24EXAMPLE 1-6 CHEMICAL 85 81 FORMULA 25 EXAMPLE 1-7 CHEMICAL 86 81 FOMULA23 + CHEMICAL FORMULA 24 EXAMPLE 1-8 FEC CHEMICAL CHEMICAL 88 81 EXAMPLE1-9 t-DFEC FORMULA 23 FORMULA 86 84 EXAMPLE 1-10 c-DFEC 27 86 84 EXAMPLE1-11 DFDMC 88 81 COMPARATIVE LIPF₆ EC + DMC — — — 81 75 EXAMPLE 1-1 1mol/kg COMPARATIVE FEC — 83 80 EXAMPLE 1-2 COMPARATIVE t-DFEC — 83 82EXAMPLE 1-3 COMPARATIVE — CHEMICAL 82 77 EXAMPLE 1-4 FORMULA 23

As shown in Table 1, in Examples 1-1 to 1-11 which included FEC or thelike as the main solvent, and the compound represented by ChemicalFormula 23 or the like as the sub solvent, the storage dischargecapacity retention ratio was higher than that in Comparative Examples1-1 to 1-4 which did not include the main solvent and the sub solvent,and the cycle discharge capacity retention ratio was higher.

More specifically, in Comparative Examples 1-2 and 1-3 which did notinclude the sub solvent and included only the main solvent, orComparative Example 1-4 which did not include the main solvent andincluded only the sub solvent, the storage discharge capacity retentionratio and the cycle discharge capacity retention ratio were higher thanthose in Comparative Example 1-1 which did not include the main solventand the sub solvent. However, in Examples 1-1 to 1-11 which included themain solvent and the sub solvent, the storage discharge capacityretention ratio and the cycle discharge capacity retention ratio werefurther higher than those in Comparative Examples 1-2 to 1-4.

Regarding the kind of the main solvent, in Examples 1-2 to 1-4 whichincluded t-DFEC, c-DFEC or DFDMC, a storage discharge capacity retentionratio equal to or higher than that in Example 1-1 which included FEC wasobtained, and a higher cycle discharge capacity retention ratio wasobtained. Moreover, regarding the kind of the sub solvent, in Examples1-5 and 1-6 which included the compound represented by Chemical Formula24 or 25, a storage discharge capacity retention ratio substantiallyequal to that in Example 1-1 which included the compound represented byChemical Formula 23, and a cycle discharge capacity retention ratioequal to that in Example 1-1 were obtained. This tendency was the samein Example 1-7 which included a mixture of the compounds represented byChemical Formulas 23 and 24. Moreover, regarding the presence or absenceof the auxiliary solvent, in Examples 1-8 to 1-11 which included thecompound represented by Chemical Formula 27, a storage dischargecapacity retention ratio and a cycle discharge capacity retention ratioequal to or higher than those in Examples 1-1 to 1-4 which did notinclude the compound were obtained.

Therefore, it was confirmed that in the secondary battery according tothe embodiment of the invention, in the case where the anode 22 includedartificial graphite as the anode active material, when the solvent ofthe electrolytic solution included at least one kind selected from thegroup consisting of the cyclic carbonate represented by Chemical Formula11 which included a halogen and the chain carbonate represented byChemical Formula 12 which included a halogen as the main solvent, and atleast one kind selected from the group consisting of the compoundsrepresented by Chemical Formulas 13, 14 and 15 as the sub solvent, thestorage characteristics in a high-temperature atmosphere were improved,and the cycle characteristics were also improved. In this case, it wasconfirmed that when a cyclic carbonate including a plurality of halogensor a chain carbonate including a plurality of halogens was used as theabove-described cyclic carbonate or the above-described chain carbonateincluding a halogen, or when the compound represented by ChemicalFormula 27 was included as the auxiliary solvent, higher effects wereobtained.

The result in the case where fluoromethyl methyl carbonate is used asthe chain carbonate represented by Chemical Formula 12 which includes ahalogen is not shown here; however, fluoromethyl methyl carbonate hasthe same properties as bis(fluoromethyl)carbonate, so it is obvious thateven in the case where fluromethyl methyl carbonate is used, the sameeffects as those in the case where bis(fluoromethyl)carbonate is usedare obtained. The same holds for the case where the cyclic carbonaterepresented by Chemical Formula 11 which includes a halogen and thechain carbonate represented by Chemical Formula 12 which includes ahalogen are mixed.

Examples 2-1 to 2-5

Secondary batteries were formed by the same steps as those in Example1-1, except that the content of the sub solvent in the solvent waschanged to 0.001 wt % (Example 2-1), 0.2 wt % (Example 2-2), 1 wt %(Example 2-3), 5 wt % (Example 2-4) and 10 wt % (Example 2-5).

When the storage characteristics and the cycle characteristics of thesecondary batteries of Examples 2-1 to 2-5 were determined, resultsshown in Table 2 were obtained.

TABLE 2 Anode active material: artificial graphite DISCHARGE CAPACITYRETENTION ELECTROLYTE SOLVENT RATIO (%) SALT MAIN SOLVENT SUB SOLVENTSTORAGE CYCLE EXAMPLE 2-1 LIPF₆ EC + DMC FEC CHEMICAL 0.001 wt % 84 80EXAMPLE 1-1 1 mol/kg FORMULA 23 0.1 wt % 86 81 EXAMPLE 2-2 0.2 wt % 8983 EXAMPLE 2-3 1 wt % 88 82 EXAMPLE 2-4 5 wt % 85 78 EXAMPLE 2-5 10 wt %84 76 COMPARATIVE LIPF₆ EC + DMC FEC — — 83 80 EXAMPLE 1-2 1 mol/kgCOMPARATIVE — CHEMICAL 0.1 wt % 82 77 EXAMPLE 1-4 FORMULA 23

As shown in Table 2, in Example 2-1 to 2-5 in which the content of thesub solvent was changed within a range from 0.001 wt % to 10 wt % bothinclusive, independent of the content, a higher storage dischargecapacity retention ratio than those in Comparative Examples 1-2 and 1-4was obtained. Regarding the cycle discharge capacity retention ratio,there was a tendency that as the content of the sub solvent increased,the cycle discharge capacity retention ratio was increased, thendecreased, and when the content of the sub solvent was reduced to 0.001wt %, or increased to 10 wt %, the cycle discharge capacity retentionratio was substantially constant. In this case, when the content of thesub solvent was 1 wt % or less, a cycle discharge capacity retentionratio equal to or higher than that in Comparative Examples 1-2 and 1-4was obtained, and when the content was 0.1 wt % or over, a higher cycledischarge capacity retention ratio than that in Comparative Examples 1-2and 1-4 was obtained.

Therefore, it was confirmed that in the above-described secondarybattery according to the embodiment of the invention, in the case wherethe solvent of the electrolytic solution included the compoundrepresented by Chemical Formula 23 as the sub solvent, when the contentof the sub solvent was within a range from 0.001 wt % to 10 wt % bothinclusive, the storage characteristics in a high-temperature atmospherewere improved, and when the content was within a range from 0.001 wt %to 1 wt % both inclusive, the cycle characteristics were secured, andwhen the content was within a range from 0.1 wt % to 1 wt % bothinclusive, the cycle characteristics were also improved.

Examples 3-1 to 3-4

Secondary batteries were formed by the same steps as those in Example1-1, except that as other solvents, vinylene carbonate (VC; Example3-1), propene sultone (PRS: Example 3-2), succinic anhydride (SCAH:Example 3-3) and sulfobenzoic anhydride (SBAH; Example 3-4) were used.At that time, the content of VC or the like in the solvent was 1 wt %.

When the storage characteristics and the cycle characteristics of thesecondary batteries of Examples 3-1 to 3-4 were determined, resultsshown in Table 3 were obtained.

TABLE 3 Anode active material: artificial graphite DISCHARGE CAPACITYRETENTION ELECTROLYTE SOLVENT RATIO (%) SALT MAIN SOLVENT SUB SOLVENTOTHERS STORAGE CYCLE EXAMPLE 1-1 LIPF₆ EC + DMC FEC CHEMICAL — 86 81EXAMPLE 3-1 1 mol/kg FORMULA 23 VC 87 82 EXAMPLE 3-2 PRS 90 81 EXAMPLE3-3 SCAH 90 82 EXAMPLE 3-4 SBAH 90 83

As shown in Table 3, in Examples 3-1 to 3-4 in which the solventincluded VC or the like, a higher storage discharge capacity retentionratio than that in Example 1-1 in which the solvent did not include theother solvent was obtained, and a cycle discharge capacity retentionratio equal to or higher than that in Example 1-1 was obtained.

Therefore, it was confirmed that in the secondary battery according tothe embodiment of the invention, when the solvent of the electrolyticsolution included a cyclic carbonate having an unsaturated bond, asultone or an acid anhydride, higher effects were obtained.

Examples 4-1 to 4-3

Secondary batteries were formed by the same steps as those in Example1-1, except that as the electrolyte salt, lithium tetrafluoroborate(LiBF₄: Example 4-1), the compound represented by Chemical Formula 30(6)as the compound represented by Chemical Formula 28 (Example 4-2), or thecompound represented by Chemical Formula 34(2) as the compoundrepresented by Chemical Formula 32 (Example 4-3) was added. At thattime, the concentration of LiPF₆ in the electrolytic solution was 0.9mol/kg, and the concentration of LiBF₄ or the like was 0.1 mol/kg.

Comparative Example 4

A secondary battery was formed by the same steps as those in Example4-2, except that FEC was not included as the main solvent.

When the storage characteristics and the cycle characteristics of thesecondary batteries of Examples 4-3 and Comparative Example 4 weredetermined, results shown in Table 4 were obtained.

TABLE 4 Anode active material: artificial graphite DISCHARGE CAPACITYRETENTION SOLVENT RATIO (%) ELECTROLYTE SALT MAIN SOLVENT SUB SOLVENTSTORAGE CYCLE EXAMPLE 1-1 LIPF₆ EC + DMC FEC CHEMICAL 86 81 1 mol/kgFORMULA 23 EXAMPLE 4-1 LIPF₆ LiBF₄ 88 81 0.9 mol/kg 0.1 mol/kg EXAMPLE4-2 CHEMICAL 90 82 FORMULA 30(6) 0.1 mol/kg EXAMPLE 4-3 CHEMICAL 88 81FORMULA 34(2) 0.1 mol/kg COMPARATIVE LIPF₆ CHEMICAL EC + DMC — CHEMICAL82 77 EXAMPLE 4 0.9 mol/kg FORULA 30(6) FORMULA 23 0.1 mol/kg

As shown in Table 4, in Examples 4-1 to 4-3 in which the electrolytesalt included LiBF₄ higher storage discharge capacity retention ratiothan that in Example 1-1 in which the electrolyte salt did not includeLiBF₄ or the like was obtained, and a cycle discharge capacity retentionratio equal to or higher than that in Example 1-1 was obtained. InExample 4-2 which included FEC as the main solvent, the storagedischarge capacity retention ratio and the cycle discharge capacityretention ratio were higher than those in Comparative Example 4 whichdid not include FEC.

Therefore, it was confirmed that in the secondary battery according tothe embodiment of the invention, when the electrolyte salt included thecompound represented by Chemical Formula 28 or the compound representedby Chemical Formula 32, higher effects were obtained.

The result in the case where the compound represented by ChemicalFormula 31 or 33 is used as the electrolyte salt is not shown here;however, the compounds represented by Chemical Formulas 31 and 33 hasthe same properties as the compound represented by Chemical Formula 32,so it is obvious that also in the case where the compound represented byChemical Formula 31 or 33 is used, the same effects as those in the casewhere the compound represented by Chemical Formula 32 is used areobtained.

Examples 5-1 to 5-6

Secondary batteries were formed by the same steps as those in Examples1-1 to 1-3, 1-5, 1-6 and 1-8, except that as the anode active material,instead of artificial graphite, silicon was used to form the anodeactive material layer 22B, and the composition of the solvent waschanged. In the case where the anode active material layer 22B wasformed, silicon was deposited on the anode current collector 21A by anelectron beam evaporation method. Moreover, as the composition of thesolvent, as the main solvent, instead of DMC, diethyl carbonate (DEC)was used, and the content of FEC in the solvent was 5 wt %, and thecontent of the compound represented by Chemical Formula 23 was 1 wt %.

Comparative Example 5-1 to 5-4

Secondary batteries were formed by the same steps as those inComparative Examples 1-1 to 1-4, except that as in the case of Examples5-1 to 5-5, silicon was used to form the anode active material layer22B, and the composition of the solvent was changed.

When the storage characteristics and the cycle characteristics of thesecondary batteries of Examples 5-1 to 5-6 and Comparative Example 5-1to 5-4 were determined, results shown in Table 5 were obtained.

TABLE 5 Anode active material: silicon DISCHARGE CAPACITY SOLVENTRETENTION ELECTROLYTE AUXILIARY RATIO (%) SALT MAIN SOLVENT SUB SOLVENTSOLVENT STORAGE CYCLE EXAMPLE 5-1 LIPF₆ EC + DEC FEC CHEMICAL — 88 61EXAMPLE 5-2 1 mol/kg t-DFEC FORMULA 23 88 78 EXAMPLE 5-3 c-DFEC 88 78EXAMPLE 5-4 FEC CHEMICAL 87 61 FORMULA 24 EXAMPLE 5-5 CHEMICAL 86 60FORMULA 25 EXAMPLE 5-6 FEC CHEMICAL CHEMICAL 89 61 FORMULA 23 FORMULA 27COMPARATIVE LIPF₆ EC + DEC — — — 81 40 EXAMPLE 5-1 1 mol/kg COMPARATIVEFEC — 84 60 EXAMPLE 5-2 COMPARATIVE t-DFEC — 84 76 EXAMPLE 5-3COMPARATIVE — CHEMICAL 82 42 EXAMPLE 5-4 FORMULA 23

As shown in Table 5, in the case where the silicon was used as the anodeactive material to form anode active material layer 22B, substantiallythe same results as those shown in Table 1 were obtained. Morespecifically, in Example 5-1 to 5-6 which included FEC or the like asthe main solvent, and the compound represented by Chemical Formula 23 orthe like as the sub solvent, the storage discharge capacity retentionratio was higher than that in Comparative Examples 5-1 to 5-4 which didnot include the main solvent and the sub solvent, and the cycledischarge capacity retention ratio was equal or higher. Therefore, itwas confirmed that in the secondary battery according to the embodimentof the invention, in the case where the anode 22 included silicon as theanode active material, when the solvent of the electrolytic solutionincluded at least one kind selected from the group consisting of thecyclic carbonate represented by Chemical Formula 11 which included ahalogen and the chain carbonate represented by Chemical Formula 12 whichincluded a halogen as the main solvent, and at least one kind selectedfrom the group consisting of the compounds represented by ChemicalFormulas 13, 14 and 15, the storage characteristics in ahigh-temperature atmosphere were improved.

Examples 6-1 to 6-4

Secondary batteries were formed by the same steps as those in Examples2-1, 1-1, 2-4 and 2-5, except that as in the case of Examples 5-1 to5-5, silicon was used to form the anode active material layer 22B, andthe composition of the solvent was changed.

When the storage characteristics and the cycle characteristics of thesecondary batteries of Examples 6-1 to 6-4 were determined, resultsshown in Table 6 were obtained.

TABLE 6 Anode active material: silicon DISCHARGE CAPACITY RETENTIONELECTROLYTE SOLVENT RATIO (%) SALT MAIN SOLVENT SUB SOLVENT STORAGECYCLE EXAMPLE 6-1 LIPF₆ EC + DEC FEC CHEMICAL 0.001 wt % 85 60 EXAMPLE6-2 1 mol/kg FORMULA 23 0.1 wt % 86 61 EXAMPLE 5-1 1 wt % 88 61 EXAMPLE6-3 5 wt % 86 58 EXAMPLE 6-4 10 wt % 85 56 COMPARATIVE LIPF₆ EC + DECFEC — — 84 60 EXAMPLE 5-2 1 mol/kg COMPARATIVE — CHEMICAL 1 wt % 82 42EXAMPLE 5-4 FORMULA 23

As shown in Table 6, the same results as those shown in Table 2 wereobtained. More specifically, in Examples 6-1 to 6-4 in which the contentof the sub solvent was changed, when the content was within a range from0.001 wt % to 10 wt % both inclusive, a higher storage dischargecapacity retention ratio than that in Comparative Examples 5-2 and 5-4was obtained. In this case, when the content of the sub solvent was 1 wt% or less, a cycle discharge capacity retention ratio equal to or higherthan that in Comparative Examples 5-2 and 5-4 was obtained, and when thecontent was 0.1 wt % or over, a higher cycle discharge capacityretention ratio was obtained. Therefore, it was confirmed that in thesecondary battery according to the embodiment of the invention, when thecontent of the sub solvent was within a range from 0.001 wt % to 10 wt %both inclusive, the storage characteristics in a high-temperatureatmosphere were improved, and when the content was within a range from0.001 wt % to 1 wt % both inclusive, the cycle characteristics weresecured, and when the content was within a range from 0.1 wt % to 1 wt %both inclusive, the cycle characteristics were also improved.

Examples 7-1 to 7-4

Secondary batteries were formed by the same steps as those in Examples3-1 to 3-4, except that as in the case of Examples 5-1 to 5-5, siliconwas used to form the anode active material layer 22B, and thecomposition of the solvent was changed.

When the storage characteristics and the cycle characteristics of thesecondary batteries of Examples 7-1 to 7-4 were determined, resultsshown in Table 7 were obtained.

TABLE 7 Anode active material: silicon DISCHARGE CAPACITY RETENTIONELECTROLYTE SOLVENT RATIO (%) SALT MAIN SOLVENT SUB SOLVENT OTHERSSTORAGE CYCLE EXAMPLE 5-1 LIPF₆ EC + DEC FEC CHEMICAL — 88 61 EXAMPLE7-1 1 mol/kg FORMULA 23 VC 88 68 EXAMPLE 7-2 PRS 89 61 EXAMPLE 7-3 SCAH90 63 EXAMPLE 7-4 SBAH 90 72

As shown in Table 7, the same results as those in Table 3 were obtained.More specifically, in Examples 7-1 to 7-4 in which the solvent includedVC or the like, a higher storage discharge capacity retention ratio thanthat in Example 5-1 in which VC or the like was not included wasobtained, and a cycle discharge capacity retention ratio equal to orhigher than that in Example 5-1 was obtained. Therefore, it wasconfirmed that in the secondary battery according to the embodiment ofthe invention, when the solvent of the electrolytic solution includedthe cyclic carbonate including an unsaturated bond, a sultone or an acidanhydride, higher effects were obtained.

Examples 8-1 to 8-3

Secondary batteries were formed by the same steps as those in Examples4-1 to 4-3, except that as in the case of Examples 5-1 to 5-5, siliconwas used to form the anode active material layer 22B, and thecomposition of the solvent was changed.

Comparative Example 8

A secondary battery was formed by the same steps as those in ComparativeExample 4, except that as in the case of Examples 5-1 to 5-5, siliconwas used to form the anode active material layer 22B, and thecomposition of the solvent was changed.

When the storage characteristics and the cycle characteristics of thesecondary batteries of Examples 8-1 to 8-3 and Comparative Example 8were determined, results shown in Table 8 were obtained.

TABLE 8 Anode active material: silicon DISCHARGE CAPACITY RETENTIONSOLVENT RATIO (%) ELECTROLYTE SALT MAIN SOLVENT SUB SOLVENT STORAGECYCLE EXAMPLE 5-1 LIPF₆ EC + DEC FEC CHEMICAL 88 61 1 mol/kg FORMULA 23EXAMPLE 8-1 LIPF₆ LiBF₄ 89 61 0.9 mol/kg 0.1 mol/kg EXAMPLE 8-2 CHEMICAL89 64 FORMULA 30(6) 0.1 mol/kg EXAMPLE 8-3 CHEMICAL 90 61 FORMULA 34(2)0.1 mol/kg COMPARATIVE LIPF₆ CHEMICAL EC + DEC — CHEMICAL 82 50 EXAMPLE8 0.9 mol/kg FORULA 30(6) FORMULA 23 0.1 mol/kg

As shown in Table 8, the same results as those shown in Table 4 wereobtained. More specifically, in Examples 8-1 to 8-3 in which theelectrolyte salt included LiBF₄ or the like, a higher storage dischargecapacity retention ratio than that in Example 5-1 in which LiBF₄ or thelike was not included was obtained, and a cycle discharge capacityretention ratio equal to or higher than that in Examples 5-1 wasobtained. In Examples 8-2 which included FEC as the main solvent, thestorage discharge capacity retention ratio and the cycle dischargecapacity retention ratio were higher than those in Comparative Example 8which did not include FEC. Therefore, it was confirmed that in thesecondary battery according to the embodiment of the invention, when theelectrolyte salt included the compound represented by Chemical Formula28 or the compound represented by Chemical Formula 32, higher effectswere obtained.

It was confirmed from the results shown in Tables 1 to 8 that in thesecondary battery according to the embodiment of the invention,irrespective of the kind of the anode active material, when the solventof the electrolytic solution included at least one kind selected fromthe group consisting of the cyclic carbonate represented by ChemicalFormula 11 which included a halogen and the chain carbonate representedby Chemical Formula 12 which included a halogen as the main solvent, andat least one kind selected from the group consisting of the compoundsrepresented by Chemical Formulas 13, 14 and 15 as the sub solvent, thestorage characteristics in a high-temperature atmosphere were improved.Moreover, it was confirmed that when the content of the sub solvent waswithin a range from 0.001 wt % to 1 wt % both inclusive, the cyclecharacteristics in a high-temperature atmosphere was secured, and whenthe content was within a range from 0.1 wt % to 1 wt % both inclusive,the cycle characteristics were also improved.

In this case, compared to the case where a carbon material was used asthe anode active material, in the case where silicon was used as theanode active material, the rate of increase of the discharge capacityretention ratio was larger. It was considered that the result wasobtained, because when silicon which was advantageous for an increase incapacity was used, compared to the case where the carbon material wasused, the electrolytic solution was easily decomposed, so thedecomposition inhibition effect of the electrolytic solution was exertedpronouncedly.

Although the present invention is described referring to the embodimentand the examples, the invention is not limited to the embodiment and theexamples, and may be variously modified. For example, the application ofthe electrolytic solution of the invention is not limited to batteries,and the electrolytic solution may be applied to any otherelectrochemical devices in addition to the batteries. As the otherapplication, for example, a capacitor or the like is cited.

Moreover, in the above-described embodiment and the above-descriedexamples, the case where the electrolytic solution or the gelelectrolyte in which the polymer compound holds the electrolyticsolution is used as the electrolyte of the battery of the invention isdescribed; however, any other kind of electrolyte may be used. Examplesof the electrolyte include a mixture of an ion-conducting inorganiccompound such as ion-conducting ceramic, ion-conducting glass or ioniccrystal and an electrolytic solution, a mixture of another inorganiccompound and an electrolytic solution, a mixture of the inorganiccompound and a gel electrolyte, and the like.

Moreover, in the above-described embodiment and the above-describedexamples, as the battery of the invention, a lithium-ion secondarybattery in which the capacity of the anode is represented by a capacitycomponent based on insertion and extraction of lithium, and a lithiummetal secondary battery in which the capacity of the anode isrepresented by a capacity component based on precipitation anddissolution of lithium are described; however, the invention is notnecessarily limited to them. The battery of the invention is applicableto a secondary battery in which the charge capacity of an anode materialcapable of inserting and extracting lithium is smaller than the chargecapacity of a cathode, thereby the capacity of the anode includes acapacity component by insertion and extraction of lithium and a capacitycomponent by precipitation and dissolution of lithium, and isrepresented by the sum of them in the same manner.

In the above-described embodiment and the above-described examples, thecase where lithium is used as an electrode reactant is described;however, any other Group 1A element in the short form of the periodictable of the elements such as sodium (Na) or potassium (K), a Group 2Aelement in the short form of the periodic table of the elements such asmagnesium or calcium (Ca), or any other light metal such as aluminum maybe used. Also in this case, as the anode active material, the anodematerial described in the above-described embodiment may be used.

Further, in the above-described embodiment and the above-describedexamples, the case where the battery has a cylindrical type, a laminatefilm type and a coin type, and the case where the battery device has aspirally wound configuration are described as examples; however, thebattery of the invention is applicable to the case where a battery hasany other shape such as a prismatic type or a button type or the casewhere the battery device has any other configuration such as a laminateconfiguration in the same manner. Further, the invention is applicableto not only the secondary batteries but also other kinds of batteriessuch as primary batteries.

In the above-described embodiment and the above-described examples, anappropriate range, which is derived from the results of the examples, ofthe content of the compounds represented by Chemical formulas 13, 14 and15 in the solvent of the electrolytic solution of the invention isdescribed; however, the description does not exclude the possibilitythat the content is out of the above-described range. More specifically,the above-described appropriate range is a specifically preferable rangeto obtain the effects of the invention, and as long as the effects ofthe invention are obtained, the content may be deviated from theabove-described range to some extent.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A secondary battery comprising: a cathode; ananode including an anode active material, wherein the anode activematerial includes a carbon material; an electrolyte solution including asolvent and an electrolyte salt; wherein the solvent includes a firstsolvent and a fourth solvent, and at least one of a second solvent and athird solvent; wherein the first solvent includes4-fluoro-1,3-dioxolane-2-one; wherein the second solvent includesChemical Formula No. 24 represented below:

and wherein the third solvent includes Chemical Formula No. 27represented below:

wherein the fourth solvent includes Chemical Formula No. 23 representedbelow:

and the amount of Chemical Formula No. 23 in the solvent ranges from 0.1wt % to 1 wt %.
 2. The secondary battery according to claim 1, whereinthe solvent of the electrolyte solution further includes at least one ofethylene carbonate, dimethyl carbonate, a vinylene carbonate-basedcompound, vinylene carbonate, a vinyl ethylene carbonate-based compound,a methylene ethylene carbonate-based compound, a sultone, propenesultone, an acid anhydride, succinic anhydride, or sulfobenzoicanhydride.
 3. The secondary battery according to claim 1, wherein thecathode includes a cathode active material including a lithium-cobaltcomplex oxide.
 4. The secondary battery according to claim 1, whereinthe electrolyte salt includes lithium hexafluorophosphate.
 5. Thesecondary battery according to claim 1, wherein the carbon materialincludes graphite.
 6. The secondary battery according to claim 1,wherein the anode includes an anode current collector, and wherein theanode active material is provided on the anode current collector.
 7. Thesecondary battery according to claim 1, wherein the secondary battery isa lithium ion secondary battery.